Binding of E. coli heat-stable enterotoxin to rat intestinal brush borders and to basolateral membranes

Journal Article · Tue Sep 01 00:00:00 EDT 1987 · Dig. Dis. Sci.; (United States)

DOI:https://doi.org/10.1007/BF01297193· OSTI ID:6030781

Guarino, A; Cohen, M B; Overmann, G; Thompson, M R; Giannella, R A

We studied the binding of E. coli heat-stable enterotoxin (STa) to rat brush borders (BB) and to basolateral membranes (BLM) using a biologically active monoiodinated radioligand (( /sup 125/I)STa) and highly enriched BB and BLM preparations free of other significant organelle contamination. Binding of (/sup 125/I)STa to BB was specific; time-, temperature-, and pH-dependent; saturable; and partially reversible. Nonlabeled toxin competitively inhibited the binding of radioligand to BB in a dose-related manner. Scatchard analysis revealed a single class of receptors with an apparent affinity constant of 8.7 +/- 1.5 X 10(8) l/mol. Binding was not affected by amino acids, sugars, and lectins. Proteolytic enzymes significantly decreased binding, although several did so by modifying the radioligand. Trypsin inhibited binding without modifying the radioligand thus supporting the proteinaceous nature of the receptor. Since the enrichment in binding activity in the BB over the homogenate was significantly lower than the enrichment in sucrase activity, we concluded that binding activity is probably associated with other membranous domains, but direct examination revealed no binding activity on basolateral membranes.

• Research Organization: Univ. of Cincinnati College of Medicine, OH
• OSTI ID: 6030781
• Journal Information: Dig. Dis. Sci.; (United States), Vol. 32:9
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
TOXINS
BIOCHEMICAL REACTION KINETICS
RECEPTORS
CELL MEMBRANES
DOSE-RESPONSE RELATIONSHIPS
ESCHERICHIA COLI
HEAT
INHIBITION
INTESTINES
IODINE 125
LIGANDS
PEPTIDE HYDROLASES
RATS
TEMPERATURE DEPENDENCE
TIME DEPENDENCE
TRACER TECHNIQUES
ANIMALS
ANTIGENS
BACTERIA
BETA DECAY RADIOISOTOPES
BODY
CELL CONSTITUENTS
DAYS LIVING RADIOISOTOPES
DIGESTIVE SYSTEM
ELECTRON CAPTURE RADIOISOTOPES
ENERGY
ENZYMES
GASTROINTESTINAL TRACT
HYDROLASES
INTERMEDIATE MASS NUCLEI
IODINE ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
MAMMALS
MATERIALS
MEMBRANE PROTEINS
MEMBRANES
MICROORGANISMS
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANS
PROTEINS
RADIOISOTOPES
REACTION KINETICS
RODENTS
TOXIC MATERIALS
VERTEBRATES
550201* - Biochemistry- Tracer Techniques