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Evidence for an unusual transmembrane configuration of AGG3, a class C Gγ subunit of Arabidopsis
Author(s) -
Wolfenstetter Susanne,
Chakravorty David,
Kula Ryan,
Urano Daisuke,
Trusov Yuri,
Sheahan Michael B.,
McCurdy David W.,
Assmann Sarah M.,
Jones Alan M.,
Botella José R.
Publication year - 2015
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.12732
Subject(s) - heterotrimeric g protein , transmembrane domain , protein subunit , transmembrane protein , biology , extracellular , arabidopsis , cysteine , c terminus , membrane topology , biochemistry , population , microbiology and biotechnology , signal transduction , g protein , membrane , amino acid , gene , enzyme , receptor , mutant , demography , sociology
Summary Heterotrimeric G proteins are crucial for the perception of external signals and subsequent signal transduction in animal and plant cells. In both model systems, the complex comprises one G α, one G β, and one G γ subunit. However, in addition to the canonical G γ subunits (class A ), plants also possess two unusual, plant‐specific classes of G γ subunits (classes B and C ) that have not yet been found in animals. These include G γ subunits lacking the C –terminal C aa X motif (class B ), which is important for membrane anchoring of the protein; the presence of such subunits gives rise to a flexible sub‐population of G β/γ heterodimers that are not necessarily restricted to the plasma membrane. Plants also contain class C G γ subunits, which are twice the size of canonical G γ subunits, with a predicted transmembrane domain and a large cysteine‐rich extracellular C –terminus. However, neither the presence of the transmembrane domain nor the membrane topology have been unequivocally demonstrated. Here, we provide compelling evidence that AGG 3, a class C G γ subunit of A rabidopsis, contains a functional transmembrane domain, which is sufficient but not essential for plasma membrane localization, and that the cysteine‐rich C –terminus is extracellular.