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Phosphorylation of GDI and membrane cycling of rab proteins
Author(s) -
Steele-Mortimer Olivia,
Gruenberg Jean,
Clague Michael J.
Publication year - 1993
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 - 10.1016/0014-5793(93)80244-o
Subject(s) - rab , gtpase , phosphorylation , cytosol , membrane protein , chemistry , immunoprecipitation , biochemistry , microbiology and biotechnology , transport protein , protein phosphorylation , membrane , biology , protein kinase a , enzyme , gene
Membrane transport is known to be regulated by protein phosphorylation and by small GTPases of the rab family. Using specific antibodies, we have identified a 55 kDa phosphorylated protein which co‐immunoprecipitated with the cytosolic forms of rab5 and other rab proteins. We demonstrate, on the basis of its mobility in two‐dimensional electrophoresis gels and its immunological properties, that this protein is rab GDI (p55/GDI). We also found that, a minor fraction of p55/GDI is membrane associated, but, whilst also complexed with rab proteins, it is not phosphorylated. On the basis of these data we suggest that the cycling of rab proteins between membranes and cytosol is regulated by phosphorylation of p55/GDI.