Work

Identification of a Contact Site for Residue 19 of Parathyroid Hormone (PTH) and PTH-Related Protein Analogs in Transmembrane Domain Two of the Type 1 PTH Receptor

Year: 2003

Type: article

Abstract: Recent functional studies have suggested that position 19 in PTH interacts with the portion of the PTH-1 receptor (P1R) that contains the extracellular loops and seven transmembrance helices (TMs) (the J domain). We tested this hypothesis using the photoaffinity cross-linking approach. A PTHrP(1-36) analog and a conformationally constrained PTH(1-21) analog, each containing para-benzoyl-l-phenylalanine (Bpa) at position 19, each cross-linked efficiently to the P1R expressed in COS-7 cells, and digestive mapping analysis localized the cross-linked site to the interval (Leu232-Lys240) at the extracellular end of TM2. Point mutation analysis identified Ala234, Val235, and Lys240 as determinants of cross-linking efficiency, and the Lys240-->Ala mutation selectively impaired the binding of PTH(1-21) and PTH(1-19) analogs, relative to that of PTH(1-15) analogs. The findings support the hypothesis that residue 19 of the receptor-bound ligand contacts, or is close to, the P1R J domain-specifically, Lys240 at the extracellular end of TM2. The findings also support a molecular model in which the 1-21 region of PTH binds to the extracellular face of the P1R J domain as an alpha-helix.

Source: Molecular Endocrinology

DOI: 10.1210/me.2003-0275

Authors: Robert C. Gensure, Naoto Shimizu, Janet Tsang, Thomas J. Gardella

Institutions: Harvard University, Massachusetts General Hospital

Language: English

Topic: Receptor Mechanisms and Signaling

Subfield: Molecular Biology

Field: Biochemistry, Genetics and Molecular Biology

Domain: Life Sciences

Open Access status: bronze

Funders: National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases

Awards: G3498444659, Hormonal Control of Calcium Metabolism, G9000015409