Flashcards in B2.045 Molecular Mechanims for Regulating Metabolism Deck (11)
what are the 3 biological "stories" or regulation discussed?
1. isoform/tissue expression
2. allosteric regulation
3. post-translational trafficking and modification
how is GLUT4 localization regulated?
insulin stimulation and muscle contraction allow translocation of GLUT4 from vesicles to plasma membrane
discuss the relationship between ubiquitous GLUT1 tissue distribution and its value of Km=5ish
Km is similar to normal blood glucose concentrations allowing it to be effective across the range of normal glucose levels
relate the low Km=1.4 of GLUT3 to the high energy needs of the brain
this low Km allows glucose transport into the brain even in low glucose conditions because brain requires glucose as fuel even in starved state
what would be the effect of increasing GLUT4 concentration on the enzyme activity curve?
vmax would increase
km wouldn't change
how can kcat changes be visualized on an enzyme activity curve?
changes in vmax
what does sigmoidal shape tell you about an enzyme?
cooperativity is present, more than one ligand binding site
how is the insulin monomer formed?
initial mRNA codes for 110 AAs
AAs are cleaved and disulfide bridges form between two chains
what three forms can insulin take?
monomer, dimer, hexamer
what is the insulin hexamer?
inactive, storage form of insulin
bound to zinc ions for stability