The centrosome is an integral piece of cellular machinery, which is responsible for organizing the cytoskeleton and directing proper chromosome segregation during cell division. In addition, the centrosome is involved in many processes outside of cell cycle regulation such as cilia assembly and proteasome activity. Despite huge advances in understanding centrosome function, the internal organization of this structure remains something of an enigma. Among the proteins known to localize to the mammalian centrosome is the coiled-coil protein, kendrin (also pericentrin, pericentrinB, pericentrin-380).

Kendrin was recently identified as the homolog of a budding yeast spindle pole body (SPB) component Spc110. Like Spc110, kendrin is known to interact with the gamma-tubulin complex at its N-terminus and calmodulin (CaM) at its C-terminus. Using a strategy based on the organization of the yeast SPB, I attempt to broaden our understanding of the mammalian centrosome by identifying novel proteins that interact with kendrin and suggest how these interactions are important in the organization and function of this structure.

Using a yeast two-hybrid screen I recovered protein candidates that consistently show an interaction with the C-terminal portion of kendrin. Further analysis of these proteins show that they are involved in a variety of cellular functions from proteolysis to cell cycle regulation. A subset of these interactions is dependent on the co-expression of vertebrate CaM. Two candidates from this category, a proliferation-associated transcriptional regulator (PA2G4) and a kinetochore associated protein with checkpoint function (KNTC1), also co-immunoprecipitate with the kendrin fragment. In fact, KNTC1 has been shown to localize to the centrosome and function in mitosis.

In addition, I report here a practical study of physical properties of fluorescent protein tags at the yeast SPB. This work is aimed at aiding researchers in their use of fluorescent tags in microscopy.