the insulin protein is originally synthesized as a
single polypeptide preproinsulin
insulin protein: connecting polypeptide is removed after
disulfide bonds are made, result = mature insulin
regulation of protein activity may occur
at two levels
two levels of protein regulation:
regulation of gene expression (determines the amount of protein produced by the cell by limiting transcription and or translation), control of protein function (the protein is synthesized by its activity is restricted according to the needs of the cell
the folding of a polypeptide may create a specific ligand...
promotes glycogen metabolism
inactive PKA is a
tetramer: two regulatory subunits bound to two catalytic subunites
what activates PKA by binding to the regulatory subunits, causing the release of the catalytic subunits?
the kinase activity of the released catalytic subunits (in PKA) do what?
phosphorylate multiple effector proteins
feedback inhibition: allosteric regulation:
a change in the conformation of a protein that affects its activity due to the binding of regulatory molecule
feedback inhibition: the end product of a biosynthetic pathway does what?
inhibits the enzyme that catalyzes the first step of its synthesis, causing the entire pathway to shut down
ex. of GTP regulated enzyme activity
the activation of Ran
phosphorylation is necessary for what?
the activation or inactivation of many proteins
protein kinase enzymes:
transfer a phosphate group from ATP to proteins
two types of kinases (depending on target amino acids_
enzymes that remove phosphate groups from phosphorylated proteins
a small protein that is attached to a target protein and is a label for regulation or destruction
the central cylinder of the proteasome contains
the active protease domain
ubiquitylation and proteasomal degradation: a ubiquitin ligase enzyme attaches several
ubiquitins to the target protein
ubiquitylation and proteasomal degradation: a cap domain of the proteasome (a protease complex)
recognizes the polyubiquitylated target protein
ubiquitylation and proteasomal degradation: the ubiquitins are
removed and recycled
ubiquitylation and proteasomal degradation: the proteasome degrades the target protein by