Phospholipase C

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Phospholipase C (PLC) catalyzes hydrolysis of a plasma membrane phospholipid, phosphatidylinositol 4,5-bisphosphate, generating 2 second messengers, the water soluble 1,4,5-inositol trisphosphate and the membrane-associated 1,2-diacylglycerol. In mammalian tissues, several groups of PLCs have been characterized, including PLC-beta, and each group contains at least 3 isoforms. These proteins are single polypeptides, ranging in molecular mass from 65 to 154 kD (review by Alvarez et al., 1995).

Phosphoinositide-specific phospholipase C, efhand-like
Members of this family are predominantly found in phosphoinositide-specific phospholipase C. They adopt a structure consisting of a core of four alpha helices, in an EF like fold, and are required for functioning of the enzyme [1].

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

Four mammalian isozymes are known (PLCβ1–4), which differ in their function and expression patterns in vivo. We have characterized the human PLCβ1 genomic locus (PLCβ1), cloned two distinct PLCβ1 cDNAs (PLCβ1a and b) and analysed their respective expression patterns in a comprehensive panel of human tissues using quantitative TaqMan technology. The two cDNAs derive from transcripts generated through alternative splicing at their 3′ end, and are predicted to encode for PLCβ1 isoforms differing at their carboxy-terminus. The human PLCβ1 isoforms are co-expressed in the same tissues with a distinctly CNS-specific profile of expression. Quantitative differences in PLCβ1 isoform expression levels are observed in some tissues. Transient expression of epitope-tagged versions of the two isoforms followed by immunofluorescence revealed localization of the proteins to the cytoplasm and the inner side of the cell membrane. Finally, we characterized the structure of the PLCβ1 locus and confirmed its mapping to human chromosome 20.

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