The well-characterized mammalian proteins are found in renal ( IIa isoform ) and intestinal ( IIb isoform ) brush border membranes and are about 640 amino acyl residues long with 8-12 putative TMSs.
12.
When the glucose concentration in the lumen of the small intestine goes above 30mM, such as occurs in the fed-state, GLUT2 is up-regulated at the brush border membrane, enhancing the capacity of glucose transport.
13.
This regulatory protein ( factor ) interacts with a sodium / hydrogen exchanger NHE3 ( SLC9A3 ) in the brush border membrane of the proximal tubule, small intestine, and colon that plays a major role in transepithelial sodium absorption.
14.
Enteropeptidase is a serine protease ( ) consisting of a disulfide-linked heavy-chain of 82-140 kDa that anchors enterokinase in the intestinal brush border membrane and a light-chain of 35 62 kDa that contains the catalytic subunit.
