STRUCUTRAL STUDIES OF THE KAR3-VIK1, KAR3-CIK1 HETERODIMER MOTOR PROTEINS

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. This research focuses on the molecular mechanism for Kar3 which belongs to the Kinesin-14 class of motors. Members of the Kinesin-14 motors are minus-end directed, non processive kinesins that operate with a powerstroke mechanism. Kar3 represents a unique opportunity to study the common functional asymmetry in non processive multimeric kinesins, including homodimeric examples such as Ncd, as Kar3 functions as a heterodimer with either Vik1 or Cik1. Vik1 and Cik1 are not molecular motors, yet we have recently shown that Vik1 contains a globular domain that exhibits the same fold as the kinesin motor domain. This domain binds more tightly to microtubules than Kar3, but does not hydrolyze ATP. This demands the existence of intermolecular communication between the motor and non motor domains in order to generate movement. Based on sequence similarity, Cik1 is predicted to contain a motor homology domain. Thus, Katherine's research should provide valuable insight into the common functional asymmetry that manifests itself in non processive molecular motors. NMR will be used to synthesize a high capacity strep column which will aid in the purification of Kar3-Vik1 and Kar3-Cik1 heterodimers.