title: Sfi1p has conserved centrin-binding sites and an essential function in budding yeast spindle pole body duplication.
abstract: Centrins are calmodulin-like proteins present in microtubule-organizing centers. The Saccharomyces cerevisiae centrin, Cdc31p, was functionally tagged with a single Z domain of protein A, and used in pull-down experiments to isolate Cdc31p-binding proteins. One of these, Sfi1p, localizes to the half-bridge of the spindle pole body (SPB), where Cdc31p is also localized. Temperature-sensitive mutants in SFI1 show a defect in SPB duplication and genetic interactions with cdc31-1. Sfi1p contains multiple internal repeats that are also present in a Schizosaccharomyces pombe protein, which also localizes to the SPB, and in several human proteins, one of which localizes close to the centriole region. Cdc31p binds directly to individual Sfi1 repeats in a 1:1 ratio, so a single molecule of Sfi1p binds multiple molecules of Cdc31p. The centrosomal human protein containing Sfi1 repeats also binds centrin in the repeat region, showing that this centrin-binding motif is conserved.
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites / Q000502:physiology; D002118:Calcium / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D004548:Elasticity; D049452:Green Fluorescent Proteins; D006801:Humans; D007202:Indicators and Reagents / Q000378:metabolism; D008164:Luminescent Proteins / Q000235:genetics; D008969:Molecular Sequence Data; D010641:Phenotype; D012097:Repressor Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D012568:Schizosaccharomyces; D029702:Schizosaccharomyces pombe Proteins; D017386:Sequence Homology, Amino Acid; D008941:Spindle Apparatus / Q000378:metabolism*
chemical_list: C083769:CDC31 protein, S cerevisiae; D002135:Calcium-Binding Proteins; D018797:Cell Cycle Proteins; D007202:Indicators and Reagents; D008164:Luminescent Proteins; D012097:Repressor Proteins; C121820:SFI1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D029702:Schizosaccharomyces pombe Proteins; C489994:cdc31 protein, S pombe; D049452:Green Fluorescent Proteins; D002118:Calcium