title: Developmentally regulated cytokeratin gene in Xenopus laevis.
abstract: We have determined the sequence of cloned cDNAs derived from a 1,665-nucleotide mRNA which transiently accumulates during Xenopus laevis embryogenesis. Computer analysis of the deduced amino acid sequence revealed that this mRNA encodes a 47-kilodalton type I intermediate filament subunit, i.e., a cytokeratin. As is common to all intermediate filament subunits so far examined, the predicted polypeptide, named XK70, contains N- and C-terminal domains flanking a central alpha-helical rod domain. The overall amino acid homology between XK70 and a human 50-kilodalton type I keratin is 47%; homology within the alpha-helical domain is 57%. The N-terminal domain, which is not completely contained in our cDNAs, is basic, contains 42% serine plus alanine, and includes five copies of a six-amino-acid repeating unit. The C-terminal domain has a high alpha-helical content and contains a region with sequence homology to the C-terminal domains of other type I and type III intermediate filament proteins. We suggest that different keratin filament subtypes may have different functional roles during amphibian oogenesis and embryogenesis.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics; D005786:Gene Expression Regulation; D007633:Keratins / Q000235:genetics*; D008970:Molecular Weight; D012333:RNA, Messenger / Q000235:genetics; D014982:Xenopus laevis / Q000196:embryology* / Q000235:genetics
chemical_list: D012333:RNA, Messenger; D007633:Keratins; D004247:DNA