A novel tropomyosin isoform encoded by the Xenopus laevis alpha-TM gene is expressed in the brain.
A full-length cDNA clone encoding a novel non-muscle tropomyosin (nmTM) termed X alpha TMB5, as yet unidentified in vertebrates, was isolated from a Xenopus laevis (Xl) brain cDNA library. X alpha TMB5 is derived from the XL alpha-tropomyosin gene (X alpha TM), which was previously found to express striated muscle and nmTM isoforms via an alternative splicing mechanism. The deduced amino-acid sequence reveals that X alpha TMB5 contains 248 amino acids. The protein differs from the skeletal muscle alpha-TM isoform only at its NH2-terminal region. The mRNA encoding X alpha TMB5 is expressed mainly in brain and striated muscle. Genomic clone analysis reveals that, unlike mammals and avian, the X alpha TM gene is devoid of the brain-specific exon 9c. The amphibian alpha-TM gene is a complex transcription unit containing 14 exons, including two alternative promoters, two internal mutually exclusive exons, and two alternatively spliced 3' exons that encode two different COOH-terminal coding regions. Therefore, a total of at least five distinct mRNAs are expressed from the X alpha TM gene in a cell-type-specific manner.
Gaillard
C
C
UPR41 CNRS, Université de Rennes I, Rennes, France.
Thézé
N
N
Lerivray
H
H
Hardy
S
S
Lepetit
D
D
Thiébaud
P
P
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001921:Brain / Q000378:metabolism*; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000302:isolation & purification; D015870:Gene Expression; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000378:metabolism; D014335:Tropomyosin / Q000737:chemistry / Q000235:genetics*; D014982:Xenopus laevis
D018076:DNA, Complementary; D012333:RNA, Messenger; D014335:Tropomyosin