Asymmetrically distributed PAR-3 protein contributes to cell polarity and spindle alignment in early C. elegans embryos.
The par-3 gene is required for establishing polarity in early C. elegans embryos. Embryos from par-3 homozygous mothers show defects in segregation of cytoplasmic determinants and in positioning of the early cleavage spindles. We report here that the PAR-3 protein is asymmetrically distributed at the periphery of the zygote and asymmetrically dividing blastomeres of the germline lineage. The PAR-3 distribution is roughly the reciprocal of PAR-1, another protein required for establishing embryonic polarity in C. elegans. Analysis of the distribution of PAR-3 and PAR-1 in other par mutants reveals that par-2 activity is required for proper localization of PAR-3 and that PAR-3 is required for proper localization of PAR-1. In addition, the distribution of the PAR-3 protein correlates with differences in cleavage spindle orientation and suggests a mechanism by which PAR-3 contributes to control of cleavage pattern.
Section of Genetics and Development, Cornell University, Ithaca, New York 14853, USA.
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Etemad-Moghadam
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Guo
K J
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Kemphues
D000818:Animals; D001757:Blastomeres / Q000737:chemistry; D017173:Caenorhabditis elegans / Q000196:embryology* / Q000235:genetics; D029742:Caenorhabditis elegans Proteins; D002453:Cell Cycle; D016764:Cell Polarity / Q000502:physiology*; D003001:Cloning, Molecular; D004625:Embryo, Nonmammalian / Q000737:chemistry; D018507:Gene Expression Regulation, Developmental; D017238:Genes, Helminth / Q000235:genetics; D015801:Helminth Proteins / Q000032:analysis* / Q000235:genetics / Q000502:physiology; D008969:Molecular Sequence Data; D017346:Protein Serine-Threonine Kinases; D012313:RNA / Q000032:analysis; D018510:RNA, Helminth / Q000032:analysis; D017422:Sequence Analysis, DNA; D015053:Zygote / Q000737:chemistry
D029742:Caenorhabditis elegans Proteins; D015801:Helminth Proteins; D018510:RNA, Helminth; C087977:par-2 protein, C elegans; D012313:RNA; C097238:PAR-3 protein, C elegans; D017346:Protein Serine-Threonine Kinases