Cloning and Characterization of a Novel Insulin-regulated Membrane Aminopeptidase from Glut4 Vesicles

doi:10.1074/jbc.270.40.23612

Cloning and Characterization of a Novel Insulin-regulated Membrane Aminopeptidase from Glut4 Vesicles (*)

From the Department of Biochemistry, Dartmouth Medical School, Hanover, New Hampshire 03755-3844 and the
Department of Molecular Biotechnology, University of Washington, Seattle, Washington 98195

^§ To whom correspondence should be addressed. Tel.: 603-650-1615; Fax: 603-650-1128; susanna.keller{at}dartmouth.edu.

↵^¶ Present address: Dept. of Signal Transduction, Parke-Davis Pharmaceutical Research Division, Warner-Lambert Co., Ann Arbor, MI 48105.

Abstract

The insulin-regulated glucose transporter isotype GluT4 expressed only in muscle and adipose cells is sequestered in a specific secretory vesicle. These vesicles harbor another major protein, referred to as vp165 (for vesicle protein of 165 kDa), that like GluT4 redistributes to the plasma membrane in response to insulin. We describe here the cloning of vp165 and show that it is a novel member of the family of zinc-dependent membrane aminopeptidases, with the typical large extracellular catalytic domain and single transmembrane domain but with a unique extended cytoplasmic domain. The latter contains two dileucine motifs, which may be critical for the specific trafficking of vp165, since this has been shown to be the case for this motif in GluT4. However, the tissue distribution of vp165 is much wider than that of GluT4; consequently, vp165 may also function in processes unrelated to insulin action and may serve as a ubiquitous marker for a specialized regulated secretory vesicle.

Footnotes

↵* This work was supported by grants from the NIDDK, National Institutes of Health (DK 25336) (to G. E. L.), and the National Science Foundation Science and Technology Center for Molecular Biotechnology (to R. A.). The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore by hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

The nucleotide sequence(s) reported in this paper has been submitted to the GenBank™/EMBL Data Bank with accession number(s) U32990[GenBank].
↵¹ The abbreviations used are:

PCR

polymerase chain reaction

LDM

low density microsomal fraction(s)

RACE

rapid amplification of cDNA ends

nt

nucleotides

bp

base pair(s)

kb

kilobase(s).
↵² S. A. Ross, H. M. Scott, N. J. Morris, W.-Y. Leung, F. Mao, G. E. Lienhard, and S. R. Keller, manuscript in preparation.
- Received June 22, 1995.
- Revision received July 20, 1995.