Marked ion dependence of 125I-angiotensin I binding to atypical sites on Mycoplasma hyorhinis.
125I-Ang I binding to atypical sites on Mycoplasma hyorhinis-contaminated IEC-18 cell membranes increased with increasing pH and [NaCl] (ED50 at 500 mM; maximal 13-fold increase at 2 M NaCl). Alkali metal chlorides and sodium halides increased binding with rank orders of Na+ < K+ < Rb+ < Cs+ = Li+ and F- < Cl- < Br < I. Covalent cross-linking of 125I-Ang I labeled a discrete band of 97 kDa. These findings suggest that the site is not a G protein-coupled receptor, but may play a role in the sensing by Mycoplasma of the ionic composition and/or pH of its environment.
Smith
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RD
Endocrinology and Reproduction Research Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892-4510, USA. rds29@hermes.cam.ac.uk
D000803:Angiotensin I / Q000378:metabolism*; D000818:Animals; D000838:Anions / Q000494:pharmacology; D001665:Binding Sites; D002414:Cations, Monovalent / Q000494:pharmacology; D002478:Cells, Cultured / Q000382:microbiology; D006219:Halogens / Q000494:pharmacology; D007421:Intestine, Small / Q000166:cytology / Q000382:microbiology*; D007457:Iodine Radioisotopes; D008672:Metals, Alkali / Q000494:pharmacology; D009174:Mycoplasma / Q000378:metabolism*; D010455:Peptides / Q000494:pharmacology; D011485:Protein Binding / Q000187:drug effects; D051381:Rats
D000838:Anions; D002414:Cations, Monovalent; D006219:Halogens; D007457:Iodine Radioisotopes; D008672:Metals, Alkali; D010455:Peptides; D000803:Angiotensin I