Biochem - cellular Flashcards
Inhibitors of G1-to-S progression
p53 and hypophosphorylated Rb
failure of Golgi to phosphorylate mannose –> coarse facial features, clouded corneas, restricted joint movement
I cell disease
inherited lysosomal storage disorder
COP1 vs. COP2 vs. clathrin
COP1 - retrograde, Golgi to ER
COP2 - ER to Golgi
clathrin - Golgi to lysosome, plasma membrane to endosome
Structure of microtubules
heterodimers of alpha and beta tubulin
each dimer has 2 GTP
Dynein vs. kinesin
Dynein - retrograde to microtubule (+ to -)
Kinesin - anterograde to microtubule (- to +)
Collagen found in bone, skin, tendons
Type 1
decr. in osteogenesis imperfecta
Collagen found in cartilage
Type 2
Collagen found in reticulin, blood vessels
Type 3
deficient in vascular type of Ehlers-Danlos
Collagen found in basement membrane
Type 4
Defective in Alport syndrome (nephritic syndrome)
Six steps of collagen synthesis
Synthesis
Hydroxylation
Glycosylation
Exocytosis
Proteolytic processing
Cross-linking
Translation of collagen alpha chains
Collagen Synthesis (occurs in the RER)
Gly-X-Y (collagen is 1/3 glycine)
Hydroxylation of proline and lysine residues
Collagen hydroxylation (occurs in the RER)
REQUIRES VITAMIN C - def. = scurvy
Formation of procollagen via hydrogen and disulfide bonds into a triple helix
Collagen glycosylation (occurs in the RER)
Problems forming triple helix (osteogenesis imperfecta)
Cleavage of disulfide-rich terminal regions of procollagen in tropocollagen
Proteolyic processing
occurs outside fibroblasts
Reinforcement of tropocollagen by lysine-hydroxylysine cross-linkage to make collagen fibrils
Cross-linking
required copper-containg lysyl oxidase (defective = Menkes disease, look for brittle/kinky hair, growth retardation, hypotonia)
