Molecular Characterization of trans-Golgi p230

doi:10.1074/jbc.271.14.8328

Molecular Characterization of trans-Golgi p230

A HUMAN PERIPHERAL MEMBRANE PROTEIN ENCODED BY A GENE ON CHROMOSOME 6p12-22 CONTAINS EXTENSIVE COILED-COIL α-HELICAL DOMAINS AND A GRANIN MOTIF (*)

From the (1)Department of Pathology and Immunology, Monash University Medical School, Melbourne, Victoria 3181, Australia, the
Department of Clinical Immunology, Flinders Medical Center, Bedford Park, South Australia, and the
(2)Department of Medical Biochemistry, University of Cape Town Medical School, Observatory, Cape Town 7925, South Africa

^¶ To whom correspondence should be addressed:
Dept. of Pathology and Immunology, Monash University Medical School, Prahran, Victoria 3181, Australia.
Tel.: 613-9276-2713; Fax: 613-9529-6484; bht{at}cobra.path.monash.edu.au.

Abstract

Using autoantibodies from a Sjögren's syndrome patient, we have previously identified a 230-kDa peripheral membrane protein associated with the cytosolic face of the trans-Golgi (Kooy, J., Toh, B. H., Pettitt, J. M., Erlich, R. and Gleeson, P. A.(1992) J. Biol. Chem. 267, 20255-20263). Here we report the molecular cloning and sequence analysis of human p230 and the localization of its gene to chromosome 6p12-22. Partial cDNA clones, isolated from a HeLa cell cDNA library using autoantibodies, were used to obtain additional cDNAs, which together span 7695 base pairs (bp). The p230 mRNA is 7.7 kilobases. Two alternatively spliced mRNAs for p230 were detected. These differed by 21- and 63-bp insertions in the 3′-sequence, resulting in differences in amino acid sequence at the carboxyl terminus. The predicted 261-kDa protein is highly hydrophilic with 17-20% homology with many proteins containing coiled-coil domains. Apart from two proline-rich regions (amino acids 1-117 and 239-270), p230 contains a very high frequency of heptad repeats, characteristic of α-helices that form dimeric coiled-coil structures. p230 also includes the sequence ESLALEELEL (amino acids 538-546), a motif found in the granin family of acidic proteins present in secretory granules of neuroendocrine cells. This is the first report of a cytosolic Golgi protein containing a granin motif. The structural characteristics of p230 indicate that it may play a role in vesicular transport from the trans-Golgi.

Footnotes

↵^§ A National Health and Medical Research Council Australian Postdoctoral Fellow.
↵* This work was supported by grants from the Australian Research Council and a Nancy E. Pandergrast Research Fellowship of the Victorian Lupus Association. 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) U41740.
↵¹ The abbreviations used are:

SNAPs

soluble N-ethylmaleimide-sensitive fusion protein attachment proteins

SNARE

SNAP receptors

PBS

phosphate-buffered saline

PCR

polymerase chain reaction.
↵²A. C. E. Knight, unpublished results.
↵³P. A. Gleeson and G. Griffiths, unpublished results.
- Received October 3, 1995.
- Revision received December 28, 1995.