title: Interaction of a kinesin-like calmodulin-binding protein with a protein kinase.
abstract: Kinesin-like calmodulin-binding protein (KCBP) is a novel member of the kinesin superfamily that is involved in cell division and trichome morphogenesis. KCBP is unique among all known kinesins in having a myosin tail homology-4 region in the N-terminal tail and a calmodulin-binding region following the motor domain. Calcium, through calmodulin, has been shown to negatively regulate the interaction of KCBP with microtubules. Here we have used the yeast two-hybrid system to identify the proteins that interact with the tail region of KCBP. A protein kinase (KCBP-interacting protein kinase (KIPK)) was found to interact specifically with the tail region of KCBP. KIPK is related to a group of protein kinases specific to plants that has an additional sequence between subdomains VII and VIII of the conserved C-terminal catalytic domain and an extensive N-terminal region. The catalytic domain alone of KIPK interacted weakly with the N-terminal KCBP protein but strongly with full-length KCBP, whereas the noncatalytic region did not interact with either protein. The interaction of KCBP with KIPK was confirmed using coprecipitation assays. Using bacterially expressed full-length and truncated proteins, we have shown that the catalytic domain is capable of phosphorylating itself. The association of KIPK with KCBP suggests regulation of KCBP or KCBP-associated proteins by phosphorylation and/or that KCBP is involved in targeting KIPK to its proper cellular location.
authors.affiliation: Department of Biology and Program in Cell and Molecular Biology, Colorado State University, Fort Collins, Colorado 80523, USA.
authors.forename: I S
authors.initials: IS
authors.lastname: Day
authors.forename: C
authors.initials: C
authors.lastname: Miller
authors.forename: M
authors.initials: M
authors.lastname: Golovkin
authors.forename: A S
authors.initials: AS
authors.lastname: Reddy
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis; D001483:Base Sequence; D002148:Calmodulin-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D016547:Kinesins / Q000737:chemistry* / Q000378:metabolism; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D011494:Protein Kinases / Q000737:chemistry* / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D002148:Calmodulin-Binding Proteins; D010940:Plant Proteins; D011494:Protein Kinases; D016547:Kinesins