Introduction to Medical Sciences 1 - Building Blocks of Cells Part 2 - Protein Functions PDF

Introduction to Medical Sciences 1 Building Blocks of Cells Part 2 Protein functions Copyright © Brunel University London v.3 2024. All rights reserved Building Blocks of Cells Dr Ricardo Carnicer Hijazo 2024 Version 3 [email protected]...

Introduction to Medical Sciences 1 Building Blocks of Cells Part 2 Protein functions Copyright © Brunel University London v.3 2024. All rights reserved Building Blocks of Cells Dr Ricardo Carnicer Hijazo 2024 Version 3 [email protected] Copyright © Brunel University London v.3 2024. All rights reserved 5  Functions of Membrane Proteins 1. Signal 2. Transport 3. Intercellular Transduction Connections 4. Cell-Cell 5. Cell 6. Enzyme Recognition Attachment Activity Copyright © Brunel University London v.3 2024. All rights reserved 6 2. Transport Pump Carrier Channel Image showing different types of transport across the membrane. From Cell biology by Thomas D. Pollard. Ed. 2017 Copyright © Brunel University London v.3 2024. All rights reserved 7 2. Transport Pump Carrier Channel Simple diffusion Active Transport Facilitated diffusion Image showing different types of transport across the membrane. From Cell biology by Thomas D. Pollard. Ed. 2017 Copyright © Brunel University London v.3 2024. All rights reserved 8 2. Transport Pump Carrier Channel Simple diffusion Active Transport √ Facilitated diffusion √ Image showing different types of transport across the membrane. From Cell biology by Thomas D. √ Pollard. Ed. 2017 Copyright © Brunel University London v.3 2024. All rights reserved 9 2. Transport Pump Carrier Channel Image showing different types of transport across the membrane. From Cell biology by Thomas D. Pollard. Ed. 2017 Copyright © Brunel University London v.3 2024. All rights reserved 10 2. Secondary active transport It uses a concentration gradient – generated by active transport – as an energy source to move molecules against their gradient. It does not directly require a chemical source of energy such as ATP. Pump Carrier Image of the Sodium – Glucose cotransporter modified from OpenStax College, Biology Copyright © Brunel University London v.3 2024. All rights reserved 11 Pumps Pumps are membrane proteins that use energy to move ions and other solutes across membranes at relatively modest rates. Energy is conserved in the form of transmembrane electrical or chemical gradients of the transported ion or solute. ADP The potential energy in these ion ATP gradients drives a variety of energy- requiring processes. Image of a pump. From Cell biology by Thomas D. Pollard. Ed. 2017 Sodium-potassium pump Nerve impulse and muscle contraction. Proton pump ATP generation. Proton-potassium pump Stomach acidification Calcium pump Muscle contraction. 12 Ion Channels Ion channels are transmembrane open pores that will allow free diffusion of any molecule of the appropriate size and charge (without the use of energy). - Transport through channels is extremely rapid. - Channels are highly selective (Na+, K+, Ca2+, Cl-). - Channels respond to physical or chemical signals in Transport the environment: Ligand-gated (Neurotransmitters). Voltage-gated (Changes in the charges gradient). Image of an ion channel. From Cell biology by Thomas D. Pollard. Ed. 2017 Functions - Nerve impulse - Muscle contraction. - Epithelial transport of nutrients and ions. - T-cell activation. - Pancreatic beta-cell insulin release. 13 Clinical relevance Channelopathies are a group of disorders that result from abnormalities in the proteins forming the ion pores or channels. Cystic fibrosis (chloride channel), Liddle's syndrome (sodium channel) Periodic paralysis (potassium channel). Copyright © Brunel University London v.3 2024. All rights reserved 14 Coordination of pumps and ion channels Propagation of nerve impulses between nerves and muscles ATP ADP Sodium/Potassium Pump Sodium Channel Image of a cellular pump and ion channel. From Servier Medical Art. Copyright © Brunel University London v.3 2024. All rights reserved 15  Sodium/Potassium ATPase Pump ATPase: protein that consumes ATP Outside the cell Inside the cell ATP ADP Potassium Sodium Phosphate Image of the sodium potassium pump. From Servier TBL 2_Building Medical Blocks of Art. Life, Cells, Organelles Copyright © Brunel University London v.3 2024. All rights reserved 16  Sodium/Potassium ATPase Pump Sodium Channel Outside the cell Extracellular ATP ADP Nerve impulse Inside the cell Intracellular Potassium Acetylcholine Phosphate Sodium (Na+) Image of the sodium channel. From Servier Medical Art. Copyright © Brunel University London v.3 2024. All rights reserved 17 Carrier proteins Carriers facilitate movement of molecules across membranes down their concentration gradient. Carriers undergo conformational changes that allow the molecule to pass through the membrane and may work in both directions. Image of glucose transporter 1 (GLUT 1). From Cell biology by Thomas D. Pollard. Ed. 2017 Function Responsible for the facilitated diffusion of sugars, amino acids, and nucleotides. Copyright © Brunel University London v.3 2024. All rights reserved 18  Functions of Membrane Proteins 1. Signal 2. Transport 3. Intercellular Transduction Connections 4. Cell-Cell 5. Cell 6. Enzyme Recognition Attachment Activity Copyright © Brunel University London v.3 2024. All rights reserved 19  3. Intercellular connections Epithelial cell Tight junctions Actin filaments Zona adherens Desmosomes Intermediate filaments Gap junctions Image modified from Servier Medical Art. Copyright © Brunel University London v.3 2024. All rights reserved 20  3. Intercellular connections Epithelial cell Tight junctions Tight junctions Zona adherens Occluding junctions that close the gaps between cells. Act as Desmosomes a diffusion barrier. Claudins and occludins Gap junctions Image modified from Servier Medical Art. Copyright © Brunel University London v.3 2024. All rights reserved 21  3. Intercellular connections Epithelial cell Tight junctions Anchoring junctions Mechanical attachments Zona adherens between cells. Desmosomes 1. Zona adherens 2. Desmosomes Gap junctions Image modified from Servier Medical Art. Copyright © Brunel University London v.3 2024. All rights reserved 22  3. Intercellular connections Tight junctions Anchoring junctions 1. Zona adherens Zona adherens tightly connects cells in a Desmosomes continuous, belt-like manner Cadherins Vinculin and cadherins Gap junctions Image modified from Servier Medical Art. Copyright © Brunel University London v.3 2024. All rights reserved 23  3. Intercellular connections Tight junctions Anchoring junctions 2. Desmosomes Zona adherens Connecting two cells subjected Desmosomes to high levels of mechanical stress via intermediate filaments Cadherins Gap junctions Image modified from Servier Medical Art. Copyright © Brunel University London v.3 2024. All rights reserved 24  3. Intercellular connections Tight junctions Communication junctions Communicating junctions Gap junctions Zona adherens Intercellular channels that allow the passage of electrical or Desmosomes chemical signals (Ca2+, IP3) Connexins Gap junctions Image modified from Servier Medical Art. Copyright © Brunel University London v.3 2024. All rights reserved 25 4. Cell-cell recognition Cell–cell recognition is a cell's ability to distinguish one type of neighbouring cell from another. A receptor on one cell surface binds to its specific ligand on a nearby cell. Functions: - Pathogen recognition in the immune system. - Response to injury: recruitment of cells (e.g. platelets, immune cells) to damaged areas - Growth and development. Copyright © Brunel University London v.3 2024. All rights reserved 26 5. Cell-matrix interactions Collagen fibre Extracellular matrix: Network consisting of a variety of secreted proteins and proteo- glycans that provide structural support to surrounding cells. Image of the extracellular matrix. Integrin From Cell biology by Thomas D. Pollard. Ed. 2017 Presentation Title 27 Copyright © Brunel University London v.3 2024. All rights reserved 6. Enzymes Enzymes are proteins that accelerate chemical reactions in the cell. Almost all metabolic processes in the cell need the presence of an enzyme in order to occur at rates fast enough to sustain life Lactose Lactase Glucose + Galactose Image by RCH. Content is available under CC BY-SA 3.0 Copyright © Brunel University London v.3 2024. All rights reserved 28 To contact me: [email protected] Copyright © Brunel University London v.3 2024. All rights reserved