Heterogeneity of intestinal receptors for Escherichia coli heat-stable enterotoxin.
The structure of rat intestinal cell receptors for Escherichia coli heat-stable enterotoxin (ST) was investigated by affinity cross-linking to 125I-ST and analysis by denaturing gel electrophoresis. Cross-linking of labeled toxin to intestinal membranes and analysis by nonreducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) revealed five specifically labeled proteins with molecular masses of 160, 136, 78, 71, and 56 (kilodaltons) kDa. Exhaustive reduction of these samples resulted in a similar pattern of labeling. Affinity-labeled proteins were further analyzed by nonreducing SDS-PAGE, reduction of the resulting separated proteins, and further separation by SDS-PAGE in the presence of beta-mercaptoethanol. Thus, the 160-kDa band on nonreducing gels consisted of two different receptors: a 160-kDa polypeptide not further reducible and one composed of at least two subunits, one of which was the 78-kDa subunit. Similarly, the 136-kDa band on nonreducing gels consisted of a 136-kDa polypeptide not further reducible and one composed of at least two subunits, one of which was the 71-kDa subunit. The 78-, 71-, and 56-kDa subunits were not further reducible. These data suggest heterogeneity of the ST receptor subunit structure and organization in rat intestinal epithelia.
Ivens
K
K
Department of Medicine, Stanford University School of Medicine, Palo Alto, California.
Gazzano
H
H
O'Hanley
P
P
Waldman
S A
SA
D000345:Affinity Labels; D000818:Animals; D001427:Bacterial Toxins / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D003432:Cross-Linking Reagents; D004768:Enterotoxins / Q000378:metabolism*; D029968:Escherichia coli Proteins; D007413:Intestinal Mucosa / Q000378:metabolism; D007422:Intestines / Q000382:microbiology*; D046911:Macromolecular Substances; D008970:Molecular Weight; D051381:Rats; D011919:Rats, Inbred Strains; D011956:Receptors, Cell Surface / Q000378:metabolism*
D000345:Affinity Labels; D001427:Bacterial Toxins; D003432:Cross-Linking Reagents; D004768:Enterotoxins; D029968:Escherichia coli Proteins; D046911:Macromolecular Substances; D011956:Receptors, Cell Surface; C034151:heat stable toxin (E coli)