The Membrane-spanning Domains of Caveolins-1 and -2 Mediate the Formation of Caveolin Hetero-oligomers
IMPLICATIONS FOR THE ASSEMBLY OF CAVEOLAE MEMBRANES IN VIVO*
- From the Departments of ‡Cell Biology and‖Molecular Pharmacology and the **Albert Einstein Cancer Center, Albert Einstein College of Medicine, Bronx, New York 10461
Abstract
The mammalian caveolin gene family consists of caveolins-1, -2, and -3. The expression of caveolin-3 is muscle-specific. In contrast, caveolins-1 and -2 are co-expressed, and they form a hetero-oligomeric complex in many cell types, with particularly high levels in adipocytes, endothelial cells, and fibroblasts. These caveolin hetero-oligomers are thought to represent the functional assembly units that drive caveolae formation in vivo. Here, we investigate the mechanism by which caveolins-1 and -2 form hetero-oligomers. We reconstituted this reciprocal interactionin vivo and in vitro using a variety of complementary approaches, including the generation of glutathioneS-transferase fusion proteins and synthetic peptides. Taken together, our results indicate that the membrane-spanning domains of both caveolins-1 and -2 play a critical role in mediating their ability to interact with each other. This is the first demonstration that these unusual membrane-spanning regions found in the caveolin family play a specific role in protein-protein interactions.
Footnotes
-
↵* This work was supported by NCI, National Institutes of Health Grant R01-CA-80250 (to M. P. L.) and by grants from the Charles E. Culpeper Foundation (to M. P. L.), the G. Harold and Leila Y. Mathers Charitable Foundation (to M. P. L. and P. E. S.), and the Sidney Kimmel Foundation for Cancer Research (to M. P. L.).The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be 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) AF141322.
-
↵§ Recipient of a fellowship from the Cancer Research Institute.
-
↵¶ Supported by a grant from Pfizer Corp., a pilot grant from the Albert Einstein College of Medicine Diabetes Research and Training Grant, and a research grant from the American Diabetes Association.
-
↵‡ To whom correspondence should be addressed: Dept. of Molecular Pharmacology and the Albert Einstein Cancer Center, Albert Einstein College of Medicine, 1300 Morris Park Ave., Bronx, NY 10461. Tel.: 718-430-8828; Fax: 718-430-8830; E-mail: lisanti{at}aecom.yu.edu.
- Abbreviations:
- Cav
-
caveolin
- GST
-
glutathione S-transferase
- mAb
-
monoclonal antibody
- PAGE
-
polyacrylamide gel electrophoresis
- Fmoc
-
N-(9-fluorenyl)methoxycarbonyl
-
- Received February 23, 1999.
- Revision received April 8, 1999.
- The American Society for Biochemistry and Molecular Biology, Inc.
