UNSPECIFIED. (1999) A novel spliced variant of the type 1 corticotropin-releasing hormone receptor with a deletion in the seventh transmembrane domain present in the human pregnant term myometrium and fetal membranes. MOLECULAR ENDOCRINOLOGY, 13 (12). pp. 2189-2202. ISSN 0888-8809

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Abstract

CRH exerts its actions via activation of specific G protein-coupled receptors, which exist in two types, CRH-R1 and CRH-RP, and arise from different genes with multiple spliced variants. RT-PCR amplification of CRH receptor sequences from human myometrium and fetal membranes yielded cDNAs that encode a novel CRH-R type 1 spliced variant. This variant (CRH-R1d) is present in the human pregnant myometrium at term only, which suggests a physiologically important role at the end of human pregnancy and labor. The amino acid sequence of CRH-R1d is identical to the CRH-R1 alpha receptor except that it contains an exon deletion resulting in the absence of 14 amino acids in the predicted seventh transmembrane domain. Binding studies in HEK-293 cells stably expressing the CRH-R1d or CRH-R1 alpha receptors revealed that the deletion does not change the binding characteristics of the variant receptor. In contrast, studies on the G protein activation demonstrated that CRH-R1d is not well coupled to the four subtypes of G proteins (G(s), G(i), G(o), G(q)) that CRH-R1 alpha can activate. These data suggest that although the deleted segment is not important for CRH binding, it plays a crucial role in CRH receptor signal transduction. Second messenger studies of the variant receptor showed that CRH and CRH-like peptides can stimulate the adenylate cyclase system, with reduced sensitivity and potency by 10-fold compared with the CRH-R1 alpha. Furthermore, CRH failed to stimulate inositol trisphosphate production. Coexpression studies between the CRH-R1d or CRH-R1 alpha showed that this receptor does not play a role as a dominant negative receptor for CRH.

Item Type:	Journal Article
Subjects:	R Medicine > RC Internal medicine
Journal or Publication Title:	MOLECULAR ENDOCRINOLOGY
Publisher:	ENDOCRINE SOC
ISSN:	0888-8809
Date:	December 1999
Volume:	13
Number:	12
Number of Pages:	14
Page Range:	pp. 2189-2202
Publication Status:	Published
URI:	http://wrap.warwick.ac.uk/id/eprint/13934

Data sourced from Thomson Reuters' Web of Knowledge

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