Molecular Cloning of Caveolin-3, a Novel Member of the Caveolin Gene Family Expressed Predominantly in Muscle

doi:10.1074/jbc.271.4.2255

Molecular Cloning of Caveolin-3, a Novel Member of the Caveolin Gene Family Expressed Predominantly in Muscle (*)

From the (1)Whitehead Institute for Biomedical Research, Cambridge, Massachusetts 02142-1479, the
(2)Shriners Hospitals for Crippled Children, Massachusetts General Hospital, Department of Anesthesia, Harvard Medical School, Boston, Massachusetts 02114, the
(3)Department of Pathology, Mount Sinai School of Medicine, New York, New York 10029, the
(4)Department of Medicine, Cardiovascular Research Center, Massachusetts General Hospital-East, Charlestown, Massachusetts 02129, and the
(5)Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139

**To whom correspondence should be addressed:
Whitehead Inst. for Biomedical Research, 9 Cambridge Center, Cambridge, MA 02142-1479.
Tel.: 617-258-5225; Fax: 617-258-9872; lisanti{at}wi.mit.edu.

Abstract

Caveolin, a 21-24-kDa integral membrane protein, is a principal component of caveolar membranes in vivo. Caveolin interacts directly with heterotrimeric G-proteins and can functionally regulate their activity. Recently, a second caveolin gene has been identified and termed caveolin-2. Here, we report the molecular cloning and expression of a third member of the caveolin gene family, caveolin-3. Caveolin-3 is most closely related to caveolin-1 based on protein sequence homology; caveolin-1 and caveolin-3 are 65% identical and 85% similar. A single stretch of eight amino acids (FEDVIAEP) is identical in caveolin-1, −2, and −3. This conserved region may represent a “caveolin signature sequence” that is characteristic of members of the caveolin gene family. Caveolin-3 mRNA is expressed predominantly in muscle tissue types (skeletal muscle, diaphragm, and heart) and is selectively induced during the differentiation of skeletal C2C12 myoblasts in culture. In many respects, caveolin-3 is similar to caveolin-1: (i) caveolin-3 migrates in velocity gradients as a high molecular mass complex; (ii) caveolin-3 colocalizes with caveolin-1 by immunofluorescence microscopy and cell fractionation studies; and (iii) a caveolin-3-derived polypeptide functionally suppresses the basal GTPase activity of purified heterotrimeric G-proteins. Identification of a muscle-specific member of the caveolin gene family may have implications for understanding the role of caveolin in different muscle cell types (smooth, cardiac, and skeletal) as previous morphological studies have demonstrated that caveolae are abundant in these cells. Our results also suggest that other as yet unknown caveolin family members are likely to exist and may be expressed in a regulated or tissue-specific fashion.

Footnotes

↵^§ Supported by a Swiss National Science Foundation fellowship.
↵^¶ Recipient of fellowships from the Byotai-Taisha Foundation and the Mochida Memorial Foundation.
↵*This work was supported in part by a grant from the W. M. Keck Foundation to the Whitehead Fellows program (to M. P. L.), National Institutes of Health FIRST Award GM-50443 (to M. P. L.), National Institutes of Health Grants GM-49516 and DK-47618 (to H. F. L.), and a grant from Bristol-Myers-Squibb (to I. N.). 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) U31968.
↵¹ The abbreviations used are:

GDI

GDP dissociation inhibitor

MDCK

Madin-Darby canine kidney

Mes

4-morpholineethanesulfonic acid

MBS

Mes-buffered saline

PBS

phosphate-buffered saline

GAP

GTPase-activating protein

GTPS

guanosine 5′-O-(3-thiotriphosphate).
↵²M. P. Lisanti and T. Okamoto, unpublished observations.
↵³M. P. Lisanti et al., unpublished observations.
- Received September 27, 1995.
- Revision received November 10, 1995.