First Author | Villasante A | Year | 1986 |
Journal | Mol Cell Biol | Volume | 6 |
Issue | 7 | Pages | 2409-19 |
PubMed ID | 3785200 | Mgi Jnum | J:25928 |
Mgi Id | MGI:73631 | Doi | 10.1128/mcb.6.7.2409 |
Citation | Villasante A, et al. (1986) Six mouse alpha-tubulin mRNAs encode five distinct isotypes: testis-specific expression of two sister genes. Mol Cell Biol 6(7):2409-19 |
abstractText | Five mouse alpha-tubulin isotypes are described, each distinguished by the presence of unique amino acid substitutions within the coding region. Most, though not all of these isotype-specific amino acids, are clustered at the carboxy terminus. One of the alpha-tubulin isotypes described is expressed exclusively in testis and is encoded by two closely related genes (M alpha 3 and M alpha 7) which have homologous 3' untranslated regions but which differ at multiple third codon positions and in their 5' untranslated regions. We show that a subfamily of alpha-tubulin genes encoding the same testis-specific isotype also exists in humans. Thus, we conclude that the duplication event leading to a pair of genes encoding a testis-specific alpha-tubulin isotype predated the mammalian radiation, and both members of the duplicated sequence have been maintained since species divergence. A second alpha-tubulin gene, M alpha 6, is expressed ubiquitously at a low level, whereas a third gene, M alpha 4, is unique in that it does not encode a carboxy-terminal tyrosine residue. This gene yields two transcripts: a 1.8-kilobase (kb) mRNA that is abundant in muscle and a 2.4-kb mRNA that is abundant in testis. Whereas the 1.8-kb mRNA encodes a distinct alpha-tubulin isotype, the 2.4-kb mRNA is defective in that the methionine residue required for translational initiation is missing. Patterns of developmental expression of the various alpha-tubulin isotypes are presented. Our data support the view that individual tubulin isotypes are capable of conferring functional specificity on different kinds of microtubules. |