Identification of nine alternatively spliced alpha2,3-sialyltransferase, ST3Gal IV, transcripts and analysis of their expression by RT-PCR and laser-induced fluorescent capillary electrophoresis (LIF-CE) in twenty-one human tissues.

In order to characterise the candidate alpha2,3-sialyltransferases necessary for biosynthesis of the selectin ligand SLe(x) and related antigens we have cloned and sequenced, from peripheral blood leukocytes of single individuals, various transcripts from the human ST3Gal III, IV and VI genes. Our clones have revealed a considerable heterogeneity in transcript isoforms. Among our ST3Gal IV clones we isolated nine alternatively spliced transcripts covering the coding region of the human ST3Gal IV gene (A1, A1 - 12, A1 + 18, A2, A2 - 12, A2 + 18, B, B - 12 and B + 18). Five of these isotranscripts A1 - 12, A1 + 18, A2 - 12, A2 + 18 and B + 18 have not been described before. In order to investigate if the alternatively spliced isotranscripts were specific for human PBL, we analysed the expression by RT-PCR and laser-induced fluorescent capillary electrophoresis (LIF-CE) in twenty other human tissues. We found a tissue specific expression of ST3Gal IV A1, A1 - 12, A1 + 18, A2, A2 - 12, A2 + 18 and B + 18 as well as a general expression of ST3Gal IV B and B - 12 isotranscripts in all tissues examined.