Trimeric G Proteins—Surprise Witness Tells a Tale

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Science  10 Nov 1995:
Vol. 270, Issue 5238, pp. 933
DOI: 10.1126/science.270.5238.933


H. Bourne comments on an unusual polymeric crystal structure for the alpha subunit of the heterotrimeric G protein presented in this issue of Science by Mixon et al. (p. 954). Although he questions the authors' suggestion that Galpha might exist as a polymer in the cell, he shows how a domain consisting of the amino and carboxyl terminal ends of the protein, evident in the polymeric structure, may be revealing how Galpha catalyzes GTP-GDP exchange.