Protein Processing and Maturation Flashcards
collagen
a fibrous protein that provides structural integrity for tissues and organs
Type 1 collagen
contains two types of polypeptides, found in the bone, skin, tendons, heart valve
Type III collagen
contains cysteine, found in the blood vessels, newborn skin
procollagen
a soluble precursor that is synthesized first and then cleaved to form the mature molecule
fibroblasts
cells that produce collagen
consensus sequence of collagen
glycine-proline-hydroxyproline
prolyl hydroxylase
hydroxylates proline to become hydroxyproline (needs vitamin C as a cofactor)
lysyl hydroxylase
hydroxylates lysine to become hydroxylysine (needs vitamin C as a cofactor)
importance of hydroxyproline
increases the stability of the collagen helix
scurvy
results from a deficiency of ascorbic acid (vitamin C), leads to a decrease in hydroxyproline, resulting in skin legions and blood vessel fragility
collagen triple helix
secondary structure different for helicies or sheets, results from steric repulsion of proline and hydroxyproline residues
tropocollagen
formed when the N- and C- terminal procollagen ends are cleaved off
collagen fibril
spontaneously formed by tropocollagen molecules
osteogenesis imperfecta
mutations in type I collagen, brittle bones and teeth, if glycine is substituted disease is more severe, glycine is critical for triple helix formation
lysyl oxidase
oxidizes the NH3+ group at the end of the lysyl side chain to an aldehyde to form a modified amino acid, allysine, forms a covalent crosslink
