Molecular cloning and developmental expression of the alpha-2 tubulin gene of Caenorhabditis elegans.

Alpha tubulin isotypes are encoded by at least four genes designated alpha-1 to alpha-4 in the nematode Caenorhabditis elegans. We describe here, molecular cloning of the alpha-2 tubulin gene, located on chromosome I, that encodes a protein of 449 amino acids that has high homology to human, mouse and Drosophila alpha tubulins, but relatively lower homology to the yeast alpha tubulins. The alpha-2 tubulin gene is trans-spliced to the SL1 leader sequence. Northern analysis shows that the gene is increasingly transcribed during the early (L1-L3) larval stages but has a lower level of transcription in L4 L4 larvae, adults, and embryos. Using an alpha-2-lacZ fusion gene expression in transgenic animals, we show that the gene is expressed in a tissue-specific manner in the intestine, pharyngeal muscle cells, and a subset of neurons which include a class of DB and VB motor neurons in the ventral nerve cord, posterior touch receptor neurons, PLML, PLMR, in the lumbar ganglia; PVT in the pre-anal ganglion, and ALA in the dorsal ganglion in the head. Our results support the notion that tubulin structure may contribute to the functional specialization of microtubules.