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

Alternatively spliced forms have been reported for several phospholipase C (PLC) isozymes, but not for PLC-beta 2, the most abundant PLC-beta in platelets. PLC-beta 2 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 similar to 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 similar to 310 nt and similar to 265 nt, with (PLC-beta 2a) and without (PLC-beta 2b) the 45-nt sequence. Thus, two alternatively spliced forms (1181 and 1166 amino acids) of PLC-beta 2 are generated in haematopoietic cells. They differ in the carboxyl terminal sequence implicated in interaction of PLC-beta enzymes with G alpha q, particulate association and nuclear localization We propose that the PLC-beta 2 splice variants may be regulated differentially with distinct roles in signal transduction.