ASGSB 1998 Annual Meeting Abstracts

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STATHMIN PHOSPHORYLATION DURING GROWTH AND GRAVITROPIC RESPONSE OF ROOTS OF ZEA MAYS L.   T.J. Mulkey and D.A. Prentice. Life Science Dept., Indiana State Univ., Terre Haute, IN.

Stathmin (also known as pp17, prosolin, Op18, p17, P19, pp20, pp21, pp23, and 19-K) is a 19-kDa cytosolic protein which has been implicated as a relay phosphoprotein in multiple signal transduction systems. Numerous roles in signal transduction in animal systems have been identified for the twelve phosphorylated and two unphosphorylated forms of stathmin. These roles are associated with key events during growth, development and differentiation. Stathmin appears to be highly conserved protein in animals and has been identified in plants (BBRC 196:589; Plant Physiol. Biochem 36(6) 449). Our data indicates that the phosphorylation state of proteins from maize roots that are in the molecular-weight range of stathmin, and identified by Northern blots, can be alter by treatment with EDTA, calcium, indole-3-acetic acid (IAA), tetradeconoyl phorbol-13-acetate (TPA), and staurosporine. TPA induces similar phosphorylation patterns of putative stathmin proteins and elongation responses in maize root tissue as promotive concentrations of IAA. Staurosporine inhibits the phosphorylation of the putative stathmin proteins in both TPA and IAA treated roots. Additionally, staurosporine inhibits the elongation response that can be induced by TPA or IAA. Further characterization of the role of stathmin as a possible regulator of signal transduction events during root gravitropic response and elongation will be presented.

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