GTP gamma S-induced pepsinogen secretion from gastric chief cells does not require carboxyl methylation or translocation of low molecular weight (LMW) GTP-binding proteins.
We identified at least four LMW GTP-binding proteins in membrane and cytosolic fractions from dispersed gastric chief cells. Extraction of membrane-bound GTP-binding proteins with various agents revealed that these proteins are intimately associated with chief cell membranes. Upon extraction with Triton X-114, the majority of GTP-binding proteins partitioned into the detergent phase, indicative of their hydrophobic nature. Although carboxyl methylation of LMW GTP-binding proteins has been shown to regulate their localization and function, inhibitors of carboxyl methylation had no effect on GTP gamma S-induced pepsinogen secretion. Moreover, pre-permeabilization of chief cells for up to 20 min did not alter GTP gamma S-induced secretion, suggesting that the guanine nucleotide analogue interacts with membrane-bound GTP-binding proteins to elicit a secretory response.
Raffaniello
R D
RD
Gastrointestinal Cell Biology Laboratory, State University of New York-Health Science Center at Brooklyn 11203-2098.
Raufman
J P
JP
D000818:Animals; D002462:Cell Membrane / Q000737:chemistry; D002463:Cell Membrane Permeability; D003600:Cytosol / Q000737:chemistry; D005089:Exocytosis / Q000187:drug effects; D019204:GTP-Binding Proteins / Q000302:isolation & purification / Q000378:metabolism*; D005753:Gastric Mucosa / Q000187:drug effects / Q000378:metabolism*; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology*; D006168:Guinea Pigs; D008297:Male; D008745:Methylation; D008970:Molecular Weight; D010435:Pepsinogens / Q000378:metabolism*
D010435:Pepsinogens; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D019204:GTP-Binding Proteins