title: The C. elegans par-4 gene encodes a putative serine-threonine kinase required for establishing embryonic asymmetry.
abstract: During the first cell cycle of Caenorhabditis elegans embryogenesis, asymmetries are established that are essential for determining the subsequent developmental fates of the daughter cells. The maternally expressed par genes are required for establishing this polarity. The products of several of the par genes have been found to be themselves asymmetrically distributed in the first cell cycle. We have identified the par-4 gene of C. elegans, and find that it encodes a putative serine-threonine kinase with similarity to a human kinase associated with Peutz-Jeghers Syndrome, LKB1 (STK11), and a Xenopus egg and embryo kinase, XEEK1. Several strong par-4 mutant alleles are missense mutations that alter conserved residues within the kinase domain, suggesting that kinase activity is essential for PAR-4 function. We find that the PAR-4 protein is present in the gonads, oocytes and early embryos of C. elegans, and is both cytoplasmically and cortically distributed. The cortical distribution begins at the late 1-cell stage, is more pronounced at the 2- and 4-cell stages and is reduced at late stages of embryonic development. We find no asymmetry in the distribution of PAR-4 protein in C. elegans embryos. The distribution of PAR-4 protein in early embryos is unaffected by mutations in the other par genes.
authors.affiliation: Section of Genetics and Development, Cornell University, Ithaca, New York 14853, USA.
authors.forename: J L
authors.initials: JL
authors.lastname: Watts
authors.forename: D G
authors.initials: DG
authors.lastname: Morton
authors.forename: J
authors.initials: J
authors.lastname: Bestman
authors.forename: K J
authors.initials: KJ
authors.lastname: Kemphues
mesh_terms: D000091162:AMP-Activated Protein Kinase Kinases; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D019521:Body Patterning / Q000235:genetics; D017173:Caenorhabditis elegans / Q000196:embryology* / Q000201:enzymology / Q000235:genetics*; D029742:Caenorhabditis elegans Proteins; D003001:Cloning, Molecular; D017931:DNA Primers / Q000235:genetics; D005260:Female; D018507:Gene Expression Regulation, Developmental; D017238:Genes, Helminth; D015801:Helminth Proteins / Q000235:genetics* / Q000502:physiology*; D006801:Humans; D008297:Male; D008969:Molecular Sequence Data; D009154:Mutation; D010641:Phenotype; D017346:Protein Serine-Threonine Kinases / Q000235:genetics* / Q000502:physiology*; D014981:Xenopus; D029867:Xenopus Proteins
chemical_list: D029742:Caenorhabditis elegans Proteins; D017931:DNA Primers; D015801:Helminth Proteins; D029867:Xenopus Proteins; C100358:STK11 protein, Xenopus; C097238:PAR-3 protein, C elegans; D017346:Protein Serine-Threonine Kinases; C109790:STK11 protein, human; D000091162:AMP-Activated Protein Kinase Kinases