64 Questions
What is the primary function of the ECM in blood vessels, lungs, and skin?
To provide elasticity
What is the approximate percentage of glycine in collagen?
35%
What is the site of O-glycosidic linkages in collagen?
Hydroxylysine
What is the molecular weight of a collagen triple helix?
300kDa
What is the characteristic feature of the repetitive amino acid sequence in collagen?
(Gly-X-Y)n
What is the strength of the collagen triple helix compared to steel?
Stronger than steel
What is the primary function of the enzyme lysyl oxidase in collagen biosynthesis?
Formation of covalent cross-links between collagen molecules
What is the role of fibronectin in the formation of collagen fibrils?
Bind to collagen fibers and alter the kinetics of fiber formation
Which type of collagen is characterized by interruptions of the triple helix with stretches of protein lacking Gly-X-Y repeat sequences?
FACITs (Fibril-associated collagen with interrupted triple helices)
What is the function of the protein elastin in the ECM?
Allow for the stretching and recoil of the ECM
What is the name of the disorder caused by mutations in the gene for fibrillin-1?
Marfan syndrome
What is the function of the protein laminin in the basal lamina?
Anchor the basal lamina to the cells
What is the function of the glycosaminoglycan hyaluronic acid in the ECM?
Act as a lubricant in the joints
What is the name of the enzyme responsible for the degradation of glycosaminoglycans?
Hyaluronidase
What is the function of the protein syndecan in the ECM?
Act as a receptor for growth factors
What is the name of the disease caused by deficiencies in the enzyme lysyl hydroxylase?
Menkes disease
What is the primary function of the ECM in protecting organs?
To keep cells, large molecules, and microorganisms from moving to other locations
What is the characteristic feature of the collagen protein?
Repetitive amino acid sequence
What is the function of hydroxyproline in collagen?
To contribute to H-bonding between α-chains
What is the structure of the collagen triple helix?
A right-handed superhelix
What is the function of fibronectin and laminin in the ECM?
To facilitate cell adhesion
What is the composition of the ECM in different tissues?
Variable, depending on tissue function
What is the role of vitamin C in collagen biosynthesis?
To catalyze the hydroxylation of proline and lysine residues
What is the function of procollagen N-proteinase and procollagen C-proteinase?
To cleave the C- and N-terminal extension peptides from procollagen
What is the function of lysyl oxidase in collagen biosynthesis?
To catalyze the formation of covalent cross-links in collagen
What is the characteristic feature of type IV collagen?
It is characterized by interruptions of the triple helix with stretches of protein lacking Gly-X-Y repeat sequences
What is the function of fibronectin in the ECM?
To provide a scaffold for the assembly of collagen fibrils
What is the function of elastin in the ECM?
To provide tensile strength to tissues
What is the function of laminin in the basal lamina?
To anchor cells to the ECM
What is the function of glycosaminoglycans in the ECM?
To attract and bind water, maintaining tissue hydration
What is the function of proteoglycans in the ECM?
To bind and regulate the activity of growth factors
What is the function of matrix metalloproteinases in the ECM?
To catalyze the degradation of ECM proteins
What is the main function of the ECM in terms of cell movement?
To keep cells, large molecules, and microorganisms from moving to other locations
What is the characteristic feature of the repetitive amino acid sequence in collagen?
A sequence of Gly-X-Y repeats
What is the function of the pyrrolidone rings in collagen?
To permit sharp twisting and confer rigidity to the collagen triple helix
What is the composition of the ECM in terms of fibrous proteins?
Collagen, elastin, and fibrillin
What is the orientation of the α-chains in the collagen triple helix?
Left-handed α-chains wound into a right-handed superhelix
What is the function of the ECM in terms of nutrient and oxygen diffusion?
To provide a porous pathway for the diffusion of nutrients and oxygen to individual cells
What is the function of collagen in the ECM?
To provide strength and structure to tissues
What is the role of vitamin C in collagen biosynthesis?
To act as a cofactor for prolyl and lysyl hydroxylases
What is the function of fibronectin in the ECM?
To facilitate cell adhesion and migration
What is the characteristic feature of elastin?
It is a random coil protein with high elasticity
What is the function of lysyl oxidase in collagen biosynthesis?
To oxidize lysine residues, forming cross-links
What is the function of laminin in the basal lamina?
To anchor the basal lamina to the underlying ECM
What is the function of glycosaminoglycans in the ECM?
To attract and bind water, maintaining tissue hydration
What is the function of proteoglycans in the ECM?
To organize and stabilize the ECM
What is the function of matrix metalloproteinases in the ECM?
To degrade collagen and other ECM proteins
What is the characteristic feature of type IV collagen?
It is a basement membrane collagen with interruptions in the triple helix
What is the primary function of the ECM in terms of cell movement?
to restrict cell movement
What is the characteristic feature of the repetitive amino acid sequence in collagen?
Gly-X-Y repetitive sequence
What is the primary function of fibronectin and laminin in the ECM?
to facilitate cell adhesion and migration
What is the composition of the ECM in terms of non-fibrous components?
proteoglycans and glycosaminoglycans
What is the function of hydroxyproline in collagen?
to confer rigidity to collagen
What is the characteristic feature of the collagen triple helix?
a right-handed super helix
Which type of collagen is characterized by a high degree of hydroxylation of proline and lysine residues?
Type I collagen
What is the primary function of fibronectin in the ECM?
To facilitate cell adhesion and migration
Which glycosaminoglycan is responsible for the negatively charged state of the glomerular basement membrane?
Heparan sulfate
What is the function of the enzyme lysyl oxidase in collagen biosynthesis?
To form cross-links between collagen molecules
What is the characteristic feature of the repetitive amino acid sequence in collagen?
A repeating pattern of Gly-X-Y
Which type of collagen is characterized by the presence of a triple helix with interruptions?
Type IV collagen
What is the function of the protein elastin in the ECM?
To provide elasticity to tissues
What is the characteristic feature of the protein laminin in the basal lamina?
A globular structure with arm-like extensions
What is the function of proteoglycans in the ECM?
To provide ground substance and mechanical support
What is the function of matrix metalloproteinases in the ECM?
To degrade and remodel the ECM
Study Notes
Extracellular Matrix (ECM)
- ECM is a complex network of proteins and carbohydrates that provides structural support, maintains tissue architecture, and regulates various cellular functions
- Composition of ECM varies in different tissues, depending on their functions
- ECM protects organs, provides elasticity, and keeps cells, large molecules, and microorganisms in place
- ECM also provides a porous pathway for the diffusion of nutrients and oxygen to individual cells
Collagen
- Collagen is the most abundant fibrous protein in the human body (~25% of all proteins)
- Found in skin, cartilage, bones, teeth, tendons, ligaments, and cornea
- Collagen is composed of three α-chains, each approximately 1000 amino acids long, with a repeating pattern of Gly-X-Y
- Hydroxyproline and hydroxylysine are essential for collagen stability and cross-linking
- Collagen triple helix is a rod-like molecule, 300 nm long and 1.5 nm thick, with a molecular weight of 300 kDa
- Collagen has high tensile strength due to its unique structure and cross-linking
Collagen Synthesis and Modification
- Collagen synthesis occurs intracellularly, with post-translational modifications such as hydroxylation and glycosylation
- Procollagen is converted to collagen through the action of procollagen N-proteinase and procollagen C-proteinase
- Lysyl oxidase catalyzes the formation of covalent cross-links between collagen molecules
- Defects in collagen synthesis or modification can lead to genetic disorders such as osteogenesis imperfecta and Ehlers-Danlos syndrome
Elastin
- Elastin is a connective tissue protein responsible for elasticity in lung, large arterial blood vessels, and some elastic ligaments
- Elastin is synthesized as a soluble monomer, tropoelastin, which is cross-linked by lysyl oxidase to form a fibrous mesh
- Elastin has a random coil conformation, allowing it to stretch and recoil
- Defects in elastin or fibrillin can lead to diseases such as Williams-Beuren syndrome and Marfan syndrome
Fibronectin
- Fibronectin is a glycoprotein found in ECM, plasma, and on cell surfaces
- Fibronectin interacts with collagen, proteoglycans, and integrins to regulate cell adhesion and migration
- Fibronectin contains an RGD sequence that binds to integrins, mediating cell-ECM interactions
Glycosaminoglycans (GAGs)
- GAGs are unbranched polysaccharides composed of repeating disaccharides
- GAGs include hyaluronic acid, chondroitin sulfate, keratan sulfate, heparin, and heparan sulfate
- GAGs are anionic, highly hydrated, and contribute to tissue turgor and sieving properties
- GAGs are covalently linked to core proteins to form proteoglycans, which are crucial for ECM structure and function
Proteoglycans
- Proteoglycans are proteins with covalently linked GAGs
- Proteoglycans are found in all tissues, primarily in ECM, and are involved in cell signaling and behavior
- Proteoglycans can bind growth factors, modulating their effects on cells
- Defects in proteoglycan synthesis or degradation can lead to diseases such as mucopolysaccharidoses
Matrix Metalloproteinases (MMPs)
- MMPs are zinc-containing proteases that cleave ECM proteins
- MMPs are regulated by transcriptional control, proteolytic activation, and inhibition by TIMPs (tissue inhibitors of metalloproteinases)
- Coordinated expression of MMPs and TIMPs is essential for tissue growth and remodeling
- Dysregulation of MMPs has been implicated in various diseases, including cancer and atherosclerosis
Extracellular Matrix (ECM)
- ECM is a complex network of proteins and carbohydrates that provides structural support, maintains tissue architecture, and regulates various cellular functions
- Composition of ECM varies in different tissues, depending on their functions
- ECM protects organs, provides elasticity, and keeps cells, large molecules, and microorganisms in place
- ECM also provides a porous pathway for the diffusion of nutrients and oxygen to individual cells
Collagen
- Collagen is the most abundant fibrous protein in the human body (~25% of all proteins)
- Found in skin, cartilage, bones, teeth, tendons, ligaments, and cornea
- Collagen is composed of three α-chains, each approximately 1000 amino acids long, with a repeating pattern of Gly-X-Y
- Hydroxyproline and hydroxylysine are essential for collagen stability and cross-linking
- Collagen triple helix is a rod-like molecule, 300 nm long and 1.5 nm thick, with a molecular weight of 300 kDa
- Collagen has high tensile strength due to its unique structure and cross-linking
Collagen Synthesis and Modification
- Collagen synthesis occurs intracellularly, with post-translational modifications such as hydroxylation and glycosylation
- Procollagen is converted to collagen through the action of procollagen N-proteinase and procollagen C-proteinase
- Lysyl oxidase catalyzes the formation of covalent cross-links between collagen molecules
- Defects in collagen synthesis or modification can lead to genetic disorders such as osteogenesis imperfecta and Ehlers-Danlos syndrome
Elastin
- Elastin is a connective tissue protein responsible for elasticity in lung, large arterial blood vessels, and some elastic ligaments
- Elastin is synthesized as a soluble monomer, tropoelastin, which is cross-linked by lysyl oxidase to form a fibrous mesh
- Elastin has a random coil conformation, allowing it to stretch and recoil
- Defects in elastin or fibrillin can lead to diseases such as Williams-Beuren syndrome and Marfan syndrome
Fibronectin
- Fibronectin is a glycoprotein found in ECM, plasma, and on cell surfaces
- Fibronectin interacts with collagen, proteoglycans, and integrins to regulate cell adhesion and migration
- Fibronectin contains an RGD sequence that binds to integrins, mediating cell-ECM interactions
Glycosaminoglycans (GAGs)
- GAGs are unbranched polysaccharides composed of repeating disaccharides
- GAGs include hyaluronic acid, chondroitin sulfate, keratan sulfate, heparin, and heparan sulfate
- GAGs are anionic, highly hydrated, and contribute to tissue turgor and sieving properties
- GAGs are covalently linked to core proteins to form proteoglycans, which are crucial for ECM structure and function
Proteoglycans
- Proteoglycans are proteins with covalently linked GAGs
- Proteoglycans are found in all tissues, primarily in ECM, and are involved in cell signaling and behavior
- Proteoglycans can bind growth factors, modulating their effects on cells
- Defects in proteoglycan synthesis or degradation can lead to diseases such as mucopolysaccharidoses
Matrix Metalloproteinases (MMPs)
- MMPs are zinc-containing proteases that cleave ECM proteins
- MMPs are regulated by transcriptional control, proteolytic activation, and inhibition by TIMPs (tissue inhibitors of metalloproteinases)
- Coordinated expression of MMPs and TIMPs is essential for tissue growth and remodeling
- Dysregulation of MMPs has been implicated in various diseases, including cancer and atherosclerosis
Extracellular Matrix (ECM)
- ECM is a complex network of proteins and carbohydrates that provides structural support, maintains tissue architecture, and regulates various cellular functions
- Composition of ECM varies in different tissues, depending on their functions
- ECM protects organs, provides elasticity, and keeps cells, large molecules, and microorganisms in place
- ECM also provides a porous pathway for the diffusion of nutrients and oxygen to individual cells
Collagen
- Collagen is the most abundant fibrous protein in the human body (~25% of all proteins)
- Found in skin, cartilage, bones, teeth, tendons, ligaments, and cornea
- Collagen is composed of three α-chains, each approximately 1000 amino acids long, with a repeating pattern of Gly-X-Y
- Hydroxyproline and hydroxylysine are essential for collagen stability and cross-linking
- Collagen triple helix is a rod-like molecule, 300 nm long and 1.5 nm thick, with a molecular weight of 300 kDa
- Collagen has high tensile strength due to its unique structure and cross-linking
Collagen Synthesis and Modification
- Collagen synthesis occurs intracellularly, with post-translational modifications such as hydroxylation and glycosylation
- Procollagen is converted to collagen through the action of procollagen N-proteinase and procollagen C-proteinase
- Lysyl oxidase catalyzes the formation of covalent cross-links between collagen molecules
- Defects in collagen synthesis or modification can lead to genetic disorders such as osteogenesis imperfecta and Ehlers-Danlos syndrome
Elastin
- Elastin is a connective tissue protein responsible for elasticity in lung, large arterial blood vessels, and some elastic ligaments
- Elastin is synthesized as a soluble monomer, tropoelastin, which is cross-linked by lysyl oxidase to form a fibrous mesh
- Elastin has a random coil conformation, allowing it to stretch and recoil
- Defects in elastin or fibrillin can lead to diseases such as Williams-Beuren syndrome and Marfan syndrome
Fibronectin
- Fibronectin is a glycoprotein found in ECM, plasma, and on cell surfaces
- Fibronectin interacts with collagen, proteoglycans, and integrins to regulate cell adhesion and migration
- Fibronectin contains an RGD sequence that binds to integrins, mediating cell-ECM interactions
Glycosaminoglycans (GAGs)
- GAGs are unbranched polysaccharides composed of repeating disaccharides
- GAGs include hyaluronic acid, chondroitin sulfate, keratan sulfate, heparin, and heparan sulfate
- GAGs are anionic, highly hydrated, and contribute to tissue turgor and sieving properties
- GAGs are covalently linked to core proteins to form proteoglycans, which are crucial for ECM structure and function
Proteoglycans
- Proteoglycans are proteins with covalently linked GAGs
- Proteoglycans are found in all tissues, primarily in ECM, and are involved in cell signaling and behavior
- Proteoglycans can bind growth factors, modulating their effects on cells
- Defects in proteoglycan synthesis or degradation can lead to diseases such as mucopolysaccharidoses
Matrix Metalloproteinases (MMPs)
- MMPs are zinc-containing proteases that cleave ECM proteins
- MMPs are regulated by transcriptional control, proteolytic activation, and inhibition by TIMPs (tissue inhibitors of metalloproteinases)
- Coordinated expression of MMPs and TIMPs is essential for tissue growth and remodeling
- Dysregulation of MMPs has been implicated in various diseases, including cancer and atherosclerosis
Extracellular Matrix (ECM)
- ECM is a complex network of proteins and carbohydrates that provides structural support, maintains tissue architecture, and regulates various cellular functions
- Composition of ECM varies in different tissues, depending on their functions
- ECM protects organs, provides elasticity, and keeps cells, large molecules, and microorganisms in place
- ECM also provides a porous pathway for the diffusion of nutrients and oxygen to individual cells
Collagen
- Collagen is the most abundant fibrous protein in the human body (~25% of all proteins)
- Found in skin, cartilage, bones, teeth, tendons, ligaments, and cornea
- Collagen is composed of three α-chains, each approximately 1000 amino acids long, with a repeating pattern of Gly-X-Y
- Hydroxyproline and hydroxylysine are essential for collagen stability and cross-linking
- Collagen triple helix is a rod-like molecule, 300 nm long and 1.5 nm thick, with a molecular weight of 300 kDa
- Collagen has high tensile strength due to its unique structure and cross-linking
Collagen Synthesis and Modification
- Collagen synthesis occurs intracellularly, with post-translational modifications such as hydroxylation and glycosylation
- Procollagen is converted to collagen through the action of procollagen N-proteinase and procollagen C-proteinase
- Lysyl oxidase catalyzes the formation of covalent cross-links between collagen molecules
- Defects in collagen synthesis or modification can lead to genetic disorders such as osteogenesis imperfecta and Ehlers-Danlos syndrome
Elastin
- Elastin is a connective tissue protein responsible for elasticity in lung, large arterial blood vessels, and some elastic ligaments
- Elastin is synthesized as a soluble monomer, tropoelastin, which is cross-linked by lysyl oxidase to form a fibrous mesh
- Elastin has a random coil conformation, allowing it to stretch and recoil
- Defects in elastin or fibrillin can lead to diseases such as Williams-Beuren syndrome and Marfan syndrome
Fibronectin
- Fibronectin is a glycoprotein found in ECM, plasma, and on cell surfaces
- Fibronectin interacts with collagen, proteoglycans, and integrins to regulate cell adhesion and migration
- Fibronectin contains an RGD sequence that binds to integrins, mediating cell-ECM interactions
Glycosaminoglycans (GAGs)
- GAGs are unbranched polysaccharides composed of repeating disaccharides
- GAGs include hyaluronic acid, chondroitin sulfate, keratan sulfate, heparin, and heparan sulfate
- GAGs are anionic, highly hydrated, and contribute to tissue turgor and sieving properties
- GAGs are covalently linked to core proteins to form proteoglycans, which are crucial for ECM structure and function
Proteoglycans
- Proteoglycans are proteins with covalently linked GAGs
- Proteoglycans are found in all tissues, primarily in ECM, and are involved in cell signaling and behavior
- Proteoglycans can bind growth factors, modulating their effects on cells
- Defects in proteoglycan synthesis or degradation can lead to diseases such as mucopolysaccharidoses
Matrix Metalloproteinases (MMPs)
- MMPs are zinc-containing proteases that cleave ECM proteins
- MMPs are regulated by transcriptional control, proteolytic activation, and inhibition by TIMPs (tissue inhibitors of metalloproteinases)
- Coordinated expression of MMPs and TIMPs is essential for tissue growth and remodeling
- Dysregulation of MMPs has been implicated in various diseases, including cancer and atherosclerosis
This quiz covers the composition and functions of the extracellular matrix (ECM) in connective tissue, including its proteoglycans, fibrous proteins, and adhesion proteins. Learn how the ECM varies in different tissues and its role in protecting organs and providing elasticity.
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