Biology 9/23/26 InsulinMaturation&Secretion

When kinesin delivers the Rab37-supervised secretory vesicle to the end of the microtubule, It is stalled at the cortex boundary by binding directly to a protein called:

synapsin

What drops the pH of the interior of the secretory granule to protonate and release the "gatekeeper" to allow cutting of the two Rs of the inhibitory Pro domain of PC1?

V-ATPase

In the low pH state, PC1 and PC2 act to remove the ______ from proinsulin.

C peptide

PC1 is bound by an inhibitory _______ which requires low pH to be removed

PRO domain

Rab37 contact at the plasma membrane HOPS complex is acted on by a GAP so that it is now bound to GDP whereupon it is removed from the vesicle membrane by:

GDI

Once cut free, the B peptide's two endl arginines (Rs) are cut away by _____.

carboxypeptidase E

The formation of the carboxylic acid carrier of the proton found on C subunits is aided in becoming protonated by a positively charged _____ on the A protein that shifts the delocalized electrons to a localized pi bond molecular orbital.

arginine

High ATP levels are required to depolarize the membrane so that Ca++ can enter the cytoplasm to activate _______ to release the Rab37-supervised secretory vesicle from its stalled position at the actin-cortex boundary.

CaMKIII

The secretory vesicle's ______ proteins interact with the plasma membrane's _____ proteins to snap together and fuse both membranes to eject insulin into the extracellular fluid.

Snare

At pH above pH 6, the Pro domain blocks the active site of PC1 preventing it from cleaving the peptide bond between the _______ section and the C peptide section of proinsulin.

B peptide

The merry-go-round within the pH changing machine that requires high ATP concentrations to power its spinning consists of multiple C subunits that each have a ________ that carries protons from the cytoplasm to the secretory granule.

glutamate

The secretory vesicle is moved through the cortex by the ATP-powered motor protein _____.

myosin5a

Above pH 6 a "gatekeeper" _____ makes ionic bonds to two amide N-Hs within the inhibitory Pro domain's polypeptide backbone so that it can't be stretched to allow contact of the two substrate arginines (Rs) from contacting the catalytic active site.

histidine

The catalytic amino acid of PC1 (and in most proteases) is a _____ whose oxygen can cleave the peptide bond.

serine