Kendrin/pericentrin-B, a centrosome protein with homology to pericentrin that complexes with PCM-1

The centrosome is responsible for nucleating microtubules and performing ot her cellular roles. To define the organization of the centrosome more compl etely, a human anti-centrosome serum was used to screen a human cDNA librar y, and a cDNA encoding a >350 kDa centrosome protein was identified, Sequen ce analyses revealed that this novel centrosome protein contains two coiled -coil domains bounded by non-coiled regions. The N-terminal region of the p rotein, named pericentrin-B, shares 61% identity (75% similarity) with peri centrin, suggesting an evolutionary relationship between these proteins. An tibodies against pericentrin-B stain centrosomes at all stages of the cell cycle, and pericentrin-B remains associated with centrosomes following micr otubule depolymerization. Immunodepletion of neither pericentrin-B nor PCM- 1 from cellular extracts inhibited the ability of salt-stripped centrosomes to recover microtubule nucleation potential, demonstrating that neither pr otein plays a key role in microtubule nucleation processes. Moreover, the b inding of both PCM-1 and pericentrin-B with salt-stripped centrosomes requi red intact microtubules, demonstrating that the association of PCM-1 and pe ricentrin-B with centrosomes is a late event in the centrosome maturation p rocess. Finally, pericentrin-B and PCM-1 coimmunoprecipitate, suggesting th at PCM-1 and pericentrin-B form a functional complex in cells. This observa tion may help to explain the generation of anti-centrosome autoantibodies i n certain autoimmune patients and may be important for centrosome function.