BIO 2120 Exam 4 - Questions and Answers What proteins are found in the extracellular matrix that are recognized by cell surface proteins? Collagens
... [Show More] Proteoglycans Fibronectin Laminin Cellular adhesion complexes that interact with ECM proteins Transmembrane integrins of focal adhesions and hemidesmosomes How do cells interact with each other? Cells interact with each other through cell adhesion complexes including adherens junctions, desmosomes and tight junctions Basal lamina Specialized meshwork of extracellular matrix (ECM) which provides separation from the connective tissue below it. The epithelial cells make many contacts with each other through cell adhesion complexes. Also, transmembrane proteins on the cells bind with high specificity to ECM proteins Fibroblasts Crawl through the connective tissue and secrete ECM proteins. They interact primarily with the ECM via focal adhesions. They can also contact each other through cell adhesion complexes such as adherens junctions Extracellular matrix (ECM) composition Fibrous proteins such as collagens that provide strength and organization to the ECM Fibronectin Capillaries Extend into connective tissue to provide nutrients to all tissues. Capillary walls consist of endothelial cells that make tight contact with each other via cell adhesion complexes Collagen Secreted by fibroblasts Consists of three protein chains that form non-covalent interactions as they coil around each other to form a triple helical structure Mutations in collagen genes underlie the vast majority of osteogenesis imperfecta cases. Fibroblasts that secrete collagen have ___. An extensive endoplasmic reticulum due to the amount of collagen that is produced Having glycine at every third position in a collagen molecule allows for ___. Tight coiling of the triple helix because glycine is the smallest amino acid The repetitive amino acid sequence found in the triple helix domain of collagen Gly-X-Y Commonly a Proline in the X position and hydroxyproline in the Y position Where is collagen modified and processed, and why? Collagen is modified and processed as it passes through the secretory pathway of a fibroblast, so collagen triple helices can't crosslink to each other until after they are secreted. Nonhelical sequences within type IV collagen interrupt the rigid molecular structure to allow ___. Allow formation of collagen networks Glycosaminoglycans (GAGs) Protruding from the protein core of a proteoglycan Contain many sugars, and many GAGs can be attached to a proteoglycan Fibronectin Component of the ECM Contains specific amino acid sequences that interact with other molecules Can bind to other ECM molecules such as collagen and proteoglycans Cells attach to fibronectin via integrins in focal adhesion complexes Laminins Contain three polypeptide chains Major component of the basal lamina Assemble into extensive networks Specific sequences in the laminins are recognized by cell surface proteins as cells attach to the basal lamina Integrins are heterodimers of ___ and ___. alpha-integrin beta-integrin How many domains do integrins have? Three domains, including an intracellular domain, a transmembrane domain, and an extracellular domain [Show Less]