Fibrous Proteins

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

Which statement about fibrous proteins is accurate?

They have low solubility in water (correct)

They primarily function as enzymes in the cell

They contain larger amounts of irregular secondary structure than globular proteins

They are highly soluble in water

What is a typical shape of fibrous proteins?

Spherical

Globular

Irregular and asymmetrical

Long cylindrical (rod- or rope-like) (correct)

What is the primary role of fibrous proteins in the cell or organism?

Enzymatic

Transport

Regulatory

Structural (correct)

What is the result of the tandem repetition of a 7-residue segment abcdefg with a and d circled in blue, and e and g circled in pink?

Formation of an α-helical polypeptide with apolar and polar edges Signup and view all the answers

What type of structure is formed when 2 staggered anti-parallel rows of dimers combine to form a left-handed super-coiled structure called a protofilament?

Coiled coil Signup and view all the answers

What causes changes in the appearance of hair waves, as explained in the text?

Breakage and reformation of disulfide bonds in α-keratin Signup and view all the answers

What is the role of apolar edges in the α-helical polypeptide structure?

Interact with each other to form a super-helical structure containing 2 polypeptide chains Signup and view all the answers

What is the primary reason for hair being permanently waved?

Changes in the disulfide bonds of α-keratin Signup and view all the answers

What is the result of hundreds of filaments being packed together to form a fibril?

Formation of a fiber (hair) Signup and view all the answers

What is the interaction of the polar edge in the α-helical polypeptide structure?

Interacts with water on the outside of the superhelix Signup and view all the answers

What type of structure is formed when 4 protofilaments combine together?

Fibril Signup and view all the answers

What percentage of the total mammalian protein does collagen make up in the human body?

25% Signup and view all the answers

How many distinct types of collagen are there in humans?

25 Signup and view all the answers

What do fibroblasts secrete that assembles into collagen fibrils?

Tropocollagen Signup and view all the answers

Approximately what percentage of the collagen found in humans is Type I?

90% Signup and view all the answers

What is the primary amino acid sequence of collagen?

Gly-X-Y Signup and view all the answers

What is the role of central glycines in the collagen helix structure?

Allow for the tight packing of the three chains Signup and view all the answers

What is involved in crosslinking different triple helices of collagen?

Hydroxylysine Signup and view all the answers

What essential modifications are involved in collagen biosynthesis?

Hydroxylation and glycosylation Signup and view all the answers

What facilitates the assembly of collagen chains into a triple helical structure?

Molecular chaperones and enzymes Signup and view all the answers

What ensures proper protein folding, assembly, and tissue-specific distribution in collagen biosynthesis?

Precise regulation Signup and view all the answers

What characteristic and organization of collagen varies in various organs?

Banding pattern Signup and view all the answers

What is the composition of collagen?

3 left-handed polypeptide helices Signup and view all the answers

Which enzyme catalyzes collagen degradation during tissue remodeling or in response to tissue growth or injury?

Collagenase Signup and view all the answers

What is the primary location for the formation of collagen fibrils?

Extracellular space Signup and view all the answers

What is the characteristic feature of collagenopathies such as Ehlers Danlos Syndrome?

Stretchy skin and loose joints Signup and view all the answers

Which type of collagen is affected in classical Ehlers Danlos Syndrome?

Type V collagen Signup and view all the answers

What is the role of collagen in blood clot formation?

Interacts with platelets and the coagulation cascade to initiate blood clot formation Signup and view all the answers

Which genetic event can have a more severe impact on collagen helix formation?

Missense mutation Signup and view all the answers

What is the final stage in the formation of collagen fibers?

Collagen fibers Signup and view all the answers

What is the impact of a mutation affecting collagen's ability to form cross-linked fibrils?

Impacts its stability Signup and view all the answers

What physiological process does collagen contribute to?

Wound healing Signup and view all the answers

What is the incidence rate of the hypermobile type of Ehlers Danlos Syndrome?

About one in 3-5,000 Signup and view all the answers

What is the impact of collagen mutations in osteogenesis imperfecta?

Leads to fragile bones Signup and view all the answers

What is the impact of collagen degradation on tissue remodeling?

Breakdown of collagen into smaller fragments and individual amino acids Signup and view all the answers

Which protein deficiency leads to the clinical manifestation of emphysema?

α1-antitrypsin deficiency Signup and view all the answers

What is the primary function of elastin in connective tissues?

Allowing tissues to stretch and recoil Signup and view all the answers

Which connective tissue disorder is caused by mutations in the fibrillin-1 gene?

Marfan syndrome Signup and view all the answers

What is the primary reason for the resistance of α-keratins to stretching?

Presence of disulfide bridges Signup and view all the answers

What is the unique cross-link found in elastin, contributing to its elasticity?

Desmosine Signup and view all the answers

What is the impact of mutations affecting collagen production and structure in osteogenesis imperfecta?

Decreased collagen cross-linking Signup and view all the answers

What is the primary role of collagen in connective tissues?

Providing structural support Signup and view all the answers

Which enzyme catalyzes elastin degradation, leading to destruction of alveolar walls?

Neutrophil elastase Signup and view all the answers

What is the impact of vitamin C deficiency on connective tissues?

Impaired collagen production Signup and view all the answers

What is the primary composition of elastin fibers in connective tissues?

Fibrillin and desmosine Signup and view all the answers

What is the primary impact of mutations in the collagen gene on tissue integrity?

Reduced tissue stability Signup and view all the answers

What is the primary factor contributing to the stability of mature extracellular elastin?

Insolubility and random coil conformations Signup and view all the answers

Study Notes

Collagen Fiber Formation and Structure

Collagen fibers are formed from precursor alpha chains inside the endoplasmic reticulum (RER), progressing to procollagen, collagen molecules outside the cell, collagen fibrils, and finally collagen fibers.
The formation of collagen fibrils involves the assembly of individual triple helical collagen molecules into micron-length fibrils with a regular axial periodic "D-banding" pattern.
Collagen has a highly stable half-life, ranging from several days to several years, and any mutation affecting its ability to form cross-linked fibrils impacts its stability.
Collagen degradation is catalyzed by collagenases during tissue remodeling or in response to tissue growth or injury, resulting in the breakdown of collagen into smaller fragments and individual amino acids.
Collagen plays a crucial role in maintaining homeostasis by providing structural support to tissues, contributing to wound healing, blood clotting, and vascular health.
Collagen interacts with platelets and the coagulation cascade to initiate blood clot formation, contributing to the prevention of excessive bleeding and the maintenance of blood vessel integrity.
Collagenopathies, such as Ehlers Danlos Syndrome, are a heterogeneous group of connective tissue disorders characterized by stretchy skin, loose joints, and other symptoms, with various genetic causes and incidence rates.
Missense mutations in collagen can have a more severe impact than nonsense alleles, as they can act as dominant negative events, hindering proper helix formation and resulting in non-functional trimers.
Osteogenesis imperfecta, also known as brittle bone disease, is a heterogeneous group of familial disorders resulting from the loss of the triple helix, leading to fragile bones.
Classical Ehlers Danlos Syndrome affects Type V collagen, while other types are caused by pathological variants in Type III collagen or lysyl hydroxylase.
The most common type of Ehlers Danlos Syndrome is the hypermobile type, occurring with an incidence of about one in 3-5,000, and the cause is unknown.
Collagen plays a critical role in various physiological processes, including wound healing, blood clotting, and maintaining the integrity of connective tissues, contributing to overall homeostasis.

Connective Tissue Disorders and Proteins: Osteogenesis Imperfecta, Scurvy, Elastin, and More

Osteogenesis imperfecta presents in various types, with different severities and outcomes, caused by mutations affecting collagen production and structure.
Vitamin C deficiency leads to scurvy, characterized by bruising, loose teeth, and fragile capillaries due to the absence of crosslinking from ascorbate.
Elastin is a connective tissue protein with rubber-like properties, providing tissues with the ability to stretch and recoil, found in lungs, blood vessels, and skin.
Collagen and elastin are different in genetic types, structure, and synthesis, with collagen having a triple helix structure and elastin forming a random coil conformation allowing stretching.
Elastin is synthesized as a soluble linear polypeptide monomer, tropoelastin, rich in proline and lysine, and interacts with glycoprotein microfibrils outside the cell.
Elastin fibers are composed of fibrillin and elastin, with fibrillin being a glycoprotein found in microfibrils, and mutations in fibrillin-1 gene cause Marfan syndrome.
Desmosine is a tetrafunctional cross-link unique to elastin, forming an extensive interconnected network, providing elasticity to connective tissue.
Mature extracellular elastin is highly insoluble, stable, and exhibits random coil conformations, allowing it to stretch and recoil during its physiological functions.
Elastin degradation is catalyzed by neutrophil elastase, which can lead to destruction of alveolar walls and is clinically important in emphysema.
Treatment of α1-antitrypsin deficiency, which can lead to emphysema, can include the infusion of recombinant α1-antitrypsin.
α-Keratins are tough fibers found in hair, nails, and the outer epidermal layer of mammals, resistant to stretching due to their α-helical polypeptide structure and disulfide bridges.
α-Keratins are resistant to stretching under normal conditions but can be affected by moist and heat conditions, causing changes in their properties.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Test your knowledge of connective tissue disorders and proteins with this quiz. Explore topics such as collagen fiber formation, collagen degradation, and the role of collagen in maintaining homeostasis. Learn about connective tissue disorders like Ehlers Danlos Syndrome and Osteogenesis Imperfecta, as well as the properties and functions of elastin and α-Keratins.