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Thyrotropin‐releasing hormone‐induced depletion of G q α/G 11 α proteins from detergent‐insensitive membrane domains
Author(s) -
Pešanová Zuzana,
Novotný Jiřı́,
Černý Jan,
Milligan Graeme,
Svoboda Petr
Publication year - 1999
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(99)01666-x
Subject(s) - adenylyl cyclase , chemistry , membrane , receptor , membrane protein , gs alpha subunit , phosphatase , enzyme , g protein , integral membrane protein , protein subunit , biochemistry , biophysics , biology , gene
The role of detergent‐insensitive membrane domains (DIMs) in desensitisation of the G protein‐coupled receptor‐mediated hormone response was studied in clone E2M11 of HEK293 cells which stably express high levels of both thyrotropin‐releasing hormone (TRH) receptors and G 11 α G protein. DIMs were prepared by flotation in equilibrium sucrose density gradients and characterised by a panel of membrane markers representing peripheral, glycosylphosphatidylinositol‐bound as well as integral membrane proteins (caveolin, CD29, CD55, CD59, CD147, the α subunit of Na,K‐ATPase) and enzyme activities (alkaline phosphatase, adenylyl cyclase). Caveolin‐containing DIMs represented only a small fraction of the overall pool of G q α/G 11 α‐rich domains. Prolonged stimulation of E2M11 cells with TRH resulted in dramatic depletion of G q α/G 11 α from all DIMs, which was paralleled by a concomitant G q α/G 11 α increase in the high‐density gradient fractions containing the bulk‐phase membrane constituents soluble in 1% Triton X‐100. Distribution of membrane markers was unchanged under these conditions. Membrane domains thus represent a substantial structural determinant of the G protein pool relevant to desensitisation of hormone action.