Vol. 166, No. 2, 1990 January 30, 1990 BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS Pages 978-983 ISOLATION AND IDENTIFICATION OF A POLTPBPTIDB IN THE HSP 70 FAMILY THAT BINDS SUBSTANCE P Barry Oblas,* Norman D. Boyd,** Judith Luber-Narod,** Victor II. Reyes, *** and Susan g. Leeman** Department of Physiology* 9 **, Department of Pharmacology***, University of Massachusetts Medical Center 55 Lake Avenue North Worcester, MA 01655 Received December 11, 1989 s-y : During the course of an attempt to purify the substance P (SP) receptor from horse salivary glands by substance P-affinity chromatography, a polypeptide of M, = 78,000 was isolated. The first fifteen amino acid residues at the amino terminus were determined and, unexpectedly, were found to be identical with the amino terminus of a glucose-regulated protein (GRP) of the same molecular weight, a protein that has been identified as a member of the heat shock protein family. This finding raises the intriguing possibility that SP may interact in vivo with GRPs and other members of the heat shock protein family and play a role in modulating their biological activities. o 1990 Academic Press, Inc. The peptide substance P (SP) exerts at least some of its biological actions on peripheral and neuronal tissues by binding with high affinity to a receptor protein that is coupled to a guanine nucleotide binding protein (G protein) (1). Thus an important step in understanding the molecular basis for the biological actions of SP is the isolation of the protein to which it binds. The isolation of several other G protein-linked receptors [eg the Q- and B-adrenergic receptors (2, 3) and muscarinic receptors (4)] has been achieved by affinity chromatography using potent specific antagonists. Particularly important is the fact that the high affinity binding of these antagonists is not dependent upon the interaction with G proteins. However * Correspondence should be sent to: Department of Pharmacology, Massachusetts College of Pharmacy and Allied Health Science, 179 Longwood Avenue, Boston, MA 02115. Abbreviations: SDS-PAGE, sodium dodecyl sulfate-polyacrylamide gel electro- phoresis; PEG, polyethyelene glycol; Hap, heat shock protein; GRP, glucose- re ulated protein; SP, substance P; [1251]-BHSP, substance P conjugated with [I h 51]-labeled Bolton-Hunter reagent; PVDF, polyvinylidene difluoride. 0006-291X&O $1.50 Copyright 0 1990 by Academic Press, Inc. All rights of reproduction in any form reserved. 978