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Phosphorylation of the G protein α‐subunit, Gα2, of Dictyostelium discoideum requires a functional and activated Gα2
Author(s) -
Gundersen Robert E.
Publication year - 1997
Publication title -
journal of cellular biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.028
H-Index - 165
eISSN - 1097-4644
pISSN - 0730-2312
DOI - 10.1002/(sici)1097-4644(19970801)66:2<268::aid-jcb13>3.0.co;2-d
Subject(s) - phosphorylation , g alpha subunit , protein subunit , biology , serine , phosphorylation cascade , microbiology and biotechnology , protein phosphorylation , gi alpha subunit , biochemistry , signal transduction , g protein , protein kinase a , gene
The Gα2‐subunit of Dictyostelium discoideum is essential to the initial stage of the cell's developmental life cycle. In response to the extracellular chemoattractant, cAMP, Gα2 is activated and transiently phosphorylated on serine‐113 [Chen et al. (1994): J Biol Chem 269:20925‐20930]. The role of Gα2 phosphorylation remains elusive; cells expressing the S113A, nonphosphorylated mutation of Gα2 appear to proceed through the developmental phase normally. To gain insight into the function of Gα2 phosphorylation, the conditions for Gα2 phosphorylation were examined using a variety of α‐subunit point mutations and chimeras. Mutations that block the G protein activation cycle prior to or at the hydrolysis of GTP (Gα2‐S45A, Gα2‐G207A, and Gα2‐Q208L) preclude Gα2 phosphorylation in vivo. Phosphorylation of the Gα2‐Q208L mutation does however occur in an in vitro phosphorylation assay. It appears that Gα2 phosphorylation, shown previously in vivo to require the cAMP receptor, also requires signaling through the G2 pathway. Results from the in vitro assay suggest that the substrate for phosphorylation is the α‐subunit monomer. J. Cell. Biochem. 66:268‐276, 1997. © 1997 Wiley‐Liss, Inc.