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Plant GTPases, Theme and Variations

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Science's STKE  11 Apr 2000:
Vol. 2000, Issue 27, pp. tw4
DOI: 10.1126/stke.2000.27.tw4

Many signal transduction superfamilies are conserved between plant and animal cells. Of the families of small guanosine triphosphatases (GTPases) including Ras, Rab, Arf, Ran, and Rho, all but Ras proteins have been identified in plants. The Rho family consists of the Cdc42, Rac, and Rho subgroups; however, within plants, only the Rac subgroup has been observed, and is termed Rop (Rho of plants). Valster et al. review recent observations on Rop and discuss the marked differences in how Rop activity is regulated compared with Rho counterparts in animal cells. Plant Rho-GTPase activating proteins (Rho-GAPs) have been identified that have a Cdc42/Rac interactive binding (CRIB) motif that may target Rops. However, in animal cells, only downstream effectors of the small GTPase proteins (and not GAPs) contain CRIB motifs. Thus, because CRIB motifs only bind to activated GTPases, this could allow for a convenient mechanism resulting in direct Rop deactivation. Also, there is evidence of direct association between a receptor-like serine kinase, CLAVATA1, and Rop, indicating another variation on signaling pathways in plants compared with animals.

Valster, A.H., Hepler, P.K., and Chernoff, J. (2000) Plant GTPases: the Rhos in bloom. Trends Cell Biol. 10:141-146. [Online Journal]

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