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| Regulation
of Arabidopsis thaliana PI 4-kinase activity and/or localization
by its Pleckstrin Homology (PH) domain Jill Stevenson-Paulik The large (~200 kDa) alpha isoform of PI 4-kinase contains a pleckstrin homology (PH) domain, a poorly conserved 100 amino acid motif that binds polyphosphoinositides. PH domains known from other enzymes have been implicated in the targeting of signaling proteins to cellular membranes. Of interest, the PI 4-kinase alpha PH domain specifically binds PtdIns4P, the enzyme's reaction product. The immediate binding of PtdIns4P generated may protect the lipid from action of other modifying enzymes, such as PIP-kinases, or be part of the catalytic mechanism of the enzyme. It is our goal to understand the role of the Arabidopsis PI 4-kinase alpha PH-domain through a combined molecular and biochemical approach. References: Stevenson et al., 1998 |