The two isoforms of myosin light chain 2 in gilthead sea bream (Sparus aurata); alternative polyadenylation site selection and tissue expression

Myosin light chain 2 (MLC2) is an essential component of the myosin molecule, with a regulatory role in binding Ca2+. In gilthead sea bream, a MLC2 clone has been isolated and characterized, that encodes for a 170 aa peptide and contains three potential polyadenylation signals in the 3′ UTR. In this study, the isolation of three alternative transcripts of the already known MLC2 (isoform A) is reported, along with the isolation and characterization of a second MLC2 isoform (B). All three isoform A transcripts encode the same peptide but differ in the length of their 3′ UTRs (284bp, 788bp and 876bp respectively) and are generated by alternative polyadenylation site selection. Transcripts of isoform A were detected both in white and red muscle. MLC2 isoform B encodes also for a 170 aa protein. Isoform B was detected in all tissues examined (red, white, smooth and cardiac muscle, kidney, liver, spleen, brain, gills, epidermis). The differential expression of the two isoforms and of the alternative transcripts of isoform A during development is currently under study, in order to investigate the functional significance and regulation of 3′ UTR length in transcription and mRNA turnover rate