Journal article
Evaluation of prototype transmembrane 4 superfamily protein complexes and their relation to lipid rafts
The Journal of biological chemistry, Vol.276(11), pp.7974-7984
03/16/2001
DOI: 10.1074/jbc.M008650200
PMID: 11113129
Abstract
Recent literature suggests that tetraspanin proteins (transmembrane 4 superfamily; TM4SF proteins) may associate with each other and with many other transmembrane proteins to form large complexes that sometimes may be found in lipid rafts. Here we show that prototype complexes of CD9 or CD81 (TM4SF proteins) with alpha(3)beta(1) (an integrin) and complexes of CD63 (a TM4SF protein) with phosphatidylinositol 4-kinase (PtdIns 4-K) may indeed localize within lipid raft-like microdomains, as seen by three different criteria. First, these complexes localize to low density light membrane fractions in sucrose gradients. Second, CD9 and alpha(3) integrin colocalized with ganglioside GM1 as seen by double staining of fixed cells. Third, CD9-alpha3beta1 and CD81-alpha3beta1 complexes were shifted to a higher density upon cholesterol depletion from intact cells or cell lysate. However, CD9-alpha3beta1, CD81-alpha3beta1, and CD63-PtdIns 4-K complex formation itself was not dependent on localization into raftlike lipid microdomains. These complexes did not require cholesterol for stabilization, were maintained within well solubilized dense fractions from sucrose gradients, were stable at 37 degrees C, and were small enough to be included within CL6B gel filtration columns. In summary, prototype TM4SF protein complexes (CD9-alpha3beta1, CD81-alpha3beta1, and CD63-PtdIns 4-K) can be solubilized as discrete units, independent of lipid microdomains, although they do associate with microdomains resembling lipid rafts.
Details
- Title: Subtitle
- Evaluation of prototype transmembrane 4 superfamily protein complexes and their relation to lipid rafts
- Creators
- Christoph Claas - Department of Cancer Immunology and AIDS, Dana-Farber Cancer Institute and Department of Pathology, Harvard Medical School, Boston, Massachusetts 02115, USAChristopher S StippMartin E Hemler
- Resource Type
- Journal article
- Publication Details
- The Journal of biological chemistry, Vol.276(11), pp.7974-7984
- DOI
- 10.1074/jbc.M008650200
- PMID
- 11113129
- NLM abbreviation
- J Biol Chem
- ISSN
- 0021-9258
- eISSN
- 1083-351X
- Publisher
- United States
- Grant note
- GM38903 / NIGMS NIH HHS CA42368 / NCI NIH HHS
- Language
- English
- Date published
- 03/16/2001
- Academic Unit
- Molecular Physiology and Biophysics; Biology
- Record Identifier
- 9983992099702771
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