title: The sequence and expression of the divergent beta-tubulin in chicken erythrocytes.
abstract: We report here the complete sequence of a highly divergent chicken erythrocyte beta-tubulin, c beta 6, which appears to represent a major exception to the observation that the primary sequences and sites of expression of beta-tubulin isotypes are conserved within vertebrates. The amino acid sequence was deduced from overlapping cloned cDNAs identified in a chicken erythroblast cDNA library contained in the expression vector, lambda gt11. Compared with other chicken beta-tubulins, among which the maximum sequence divergence is only 8%, c beta 6-tubulin is more hydrophobic, contains seven fewer net negative charges, and exhibits a surprising 17% overall divergence in its amino acid sequence. DNA and RNA blot analyses show that c beta 6-tubulin is present as a single gene copy in the chicken genome and is specifically expressed in the bone marrow. Comparisons of RNA blots and immunoblots of various cells and tissues confirm that this beta-tubulin isotype is contained specifically in erythrocytes and thrombocytes and accounts for 75% of the beta-tubulin mRNA species contained in developing erythroblasts. Interestingly, c beta 6-tubulin exhibits 18% amino acid sequence divergence relative to MB1, the analogous hematopoietic beta-tubulin contained in mouse.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002645:Chickens; D003001:Cloning, Molecular; D004247:DNA / Q000378:metabolism; D004262:DNA Restriction Enzymes; D004912:Erythrocytes / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D009693:Nucleic Acid Hybridization; D011061:Poly A / Q000235:genetics / Q000302:isolation & purification; D012333:RNA, Messenger / Q000235:genetics / Q000302:isolation & purification; D012689:Sequence Homology, Nucleic Acid; D013045:Species Specificity; D014404:Tubulin / Q000097:blood / Q000235:genetics*
chemical_list: D012333:RNA, Messenger; D014404:Tubulin; D011061:Poly A; D004247:DNA; D004262:DNA Restriction Enzymes