Cloning and characterization of the human phosphoinositide-specific phospholipase C-beta 1 (PLC beta 1)

Phospholipase C-beta (PLC beta) catalyses the generation of inositol 1,4,5- trisphosphate (IP3) and diacylglycerol (DAG) from phosphatidylinositol 4,5- bisphosphate (IP2), a key step in the intracellular transduction of a large number of extracellular signals, including neurotransmitters and hormones modulating diverse developmental and functional aspects of the mammalian ce ntral nervous system. Four mammalian isozymes are known (PLC beta1-4), whic h differ in their function and expression patterns in vivo. We have charact erized the human PLC beta1 genomic locus (PLC beta1), cloned two distinct P LC beta1 cDNAs (PLC beta 1a and b) and analysed their respective expression patterns in a comprehensive panel of human tissues using quantitative TaqM an technology. The two cDNAs derive from transcripts generated through alte rnative splicing at their 3' end, and are predicted to encode for PLC beta1 isoforms differing at their carboxy-terminus. The human PLC beta1 isoforms are co-expressed in the same tissues with a distinctly CNS-specific profil e of expression. Quantitative differences in PLC beta1 isoform expression l evels are observed in some tissues. Transient expression of epitope-tagged versions of the two isoforms followed by immunofluorescence revealed locali zation of the proteins to the cytoplasm and the inner side of the cell memb rane. Finally, we characterized the structure of the PLC beta1 locus and co nfirmed its mapping to human chromosome 20. (C) 2000 Elsevier Science B.V. All rights reserved.