A unique isoform of phospholipase C beta 4 highly expressed in the cerebellum and eye

We report a unique isoform of PLC beta 4 in rat, PLC beta 4c, that has an a dditional 37-nucleotide exon inserted between nucleotides 3459-3460 of the previously published PLC beta 4a coding sequence. This insertion results in replacement of 22 amino acid residues at the carboxyl terminal tail of PLC beta 4a with 41 unique residues. A human EST for PLC beta 4 also contains this exon and this exon was mapped to within a 5.5 kb intron of the human P LC beta 4 gene. PLC beta 4c is the third PLC beta 4 isoform to be identifie d which has a unique carboxyl-terminal tail. PLC beta 4b differs from PLC b eta 4a by truncation 162 amino acid residues from the carboxyl terminus whi ch are replaced with 10 distinct amino acid residues. Reverse transcription -polymerase chain reaction experiments show that both PLC beta 4a and PLC b eta 4c mRNA are expressed throughout the rat brain and that PLC beta 4c mRN A is highly expressed in the eye and cerebellum. RNase protection assays de monstrate that both PLC beta 4a and PLC beta 4c transcripts are abundant in the cerebellum. The different carboxyl terminal tails of PLC beta 4 isofor ms may allow for differential targeting and subcellular localization, contr ibuting to regulation of PLC beta 4-mediated signal transduction. (C) 1999 Elsevier Science B.V. All rights reserved.