α1-Thymosin, α2-interferon, and the LKEKK syntetic peptide inhibit the binding of the B subunit of the cholera toxin to intestinal epithelial cell membranes

• Published in: Russian journal of bioorganic chemistry Vol. 43; no. 6; pp. 673 - 677
• Main Authors: Navolotskaya, E. V., Sadovnikov, V. B., Zinchenko, D. V., Vladimirov, V. I., Zolotarev, Y. A.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01.11.2017; Springer Nature B.V
• Subjects: Binding; Biochemistry; Biomedical and Life Sciences; Biomedicine; Bioorganic Chemistry; Cell membranes; Cholera; Interferon; Life Sciences; Membranes; Organic Chemistry; Peptides; Small intestine; peptides; the B subunit of the cholera toxin; receptors; interferon-α; thymosin-α
• ISSN: 1068-1620; 1608-330X
• DOI: 10.1134/S1068162017060115

The 125 I-labeled B-subunit of the cholera toxin ([125I]CT-B, specific activity of 98 Ci/mmol) was prepared. This subunit was shown to be bound to the membranes which were isolated from epithelial cells of a mucous tunic of the rat thin intestine with high affinity ( K d = 3.7 nM). The binding of the labeled protein was inhibited by the unlabeled α 2 -interferon (IFN-α 2 ), α 1 -thymosin, (TM-α 1 ), and the LKEKK synthetic peptide corresponding to the 16–20 sequence of TM-α 1 and the 131–135 sequence of human IFN-α 2 (Ki 1.0, 1.5, and 2.0 nM, respectively), whereas the KKEKL unlabeled synthetic peptide did not inhibit the binding ( K i > 100 μМ). The LKEKK peptide and CT-B were shown to dose-dependently increase an activity of the soluble guanylate cyclase (sGC) in the concentration range from 10 to 1000 nM. Thus, the binding of TM- α 1 , IFN-α 2 , and the LKEKK peptide to the CT-B receptor on a surface of the epithelial cells of the mucous tunic of the rat thin intestine resulted in an increase in the intracellular level of cGMP.