A survey of the alpha-tubulin gene family in chicken: unexpected sequence heterogeneity in the polypeptides encoded by five expressed genes.
To characterize the alpha-tubulin gene family in chicken, we have isolated five chicken alpha-tubulin genes and determined the majority of the sequences of the encoded polypeptides. Three of these (c alpha 3, c alpha 5/6 and c alpha 8) encode novel, expressed alpha-tubulins that have not previously been analyzed, whereas one gene segment is a pseudogene and another appears capable of encoding a functional subunit (although we were unable to document its expression in a survey of chicken tissues). Together with two additional expressed, functional alpha-tubulins reported earlier, we conclude that the chicken alpha-tubulin family is comprised of at least five functional genes whose polypeptide products are substantially more heterogeneous than found in preceding analyses of vertebrate alpha-tubulins. Comparison of the amino acid sequences reveals that the five polypeptides are between 96 and 83% identical, with the extreme carboxy-terminal residues representing a highly heterogeneous variable domain. Since some alpha-tubulins undergo cyclic post-translational removal and readdition of a carboxy-terminal tyrosine, the notable sequence divergence in this domain suggests that individual tubulins probably participate to different extents in this modification cycle.
Pratt
L F
LF
Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205.
Cleveland
D W
DW
D000483:Alleles; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002642:Chick Embryo; D002645:Chickens / Q000235:genetics*; D004247:DNA / Q000235:genetics; D005796:Genes; D014644:Genetic Variation; D008969:Molecular Sequence Data; D011544:Pseudogenes; D014158:Transcription, Genetic; D014404:Tubulin / Q000235:genetics*
D014404:Tubulin; D004247:DNA