Evidence for two alternatively spliced forms of phospholipase C-β2 in haematopoietic cells

Abstract

Alternatively spliced forms have been reported for several phospholipase C (PLC) isozymes, but not for PLC-β2, the most abundant PLC-β in platelets, PLC-β2 cDNA cloned from the HL-60-cell cDNA library is 3543 bases long, coding for 1181 amino acids. Compared with the published sequence, a deletion of 45 nucleotides (2755-2799 nt, amino acids 864-878) was detected in platelet and leucocyte mRNA amplified by reverse transcription (RT) polymerase chain reaction (PCR) using primers corresponding to 1814-1838 nt (forward) and 3328-3352 nt (reverse). Amplification of genomic DNA using primers corresponding to 2575-2596 nt and 2864-2885 nt yielded a ~750 bp product; restriction analysis and sequencing revealed the 45-bp exon flanked by introns of 198 bp and 118 bp. Amplification of leucocyte and platelet cDNA using the same primers yielded products of ~310 nt and ~265 nt, with (PLC-β2a) and without (PLC- β2b) the 45-nt sequence. Thus, two alternatively spliced forms (1181 and 1166 amino acids) of PLC-β2 are generated in haematopoietic cells. They differ in the carboxyl terminal sequence implicated in interaction of PLG-β enzymes with Gαq, particulate association and nuclear localization. We propose that the PLC-β2 splice variants may be regulated differentially with distinct roles in signal transduction.