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Cloning and characterization of a phospholipase C‐β isoform from the sea urchin Lytechinus pictus
Author(s) -
Kulisz Andre,
Dowal Louisa,
Scarlata Suzanne,
Shen Sheldon S.
Publication year - 2005
Publication title -
development, growth and differentiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.864
H-Index - 66
eISSN - 1440-169X
pISSN - 0012-1592
DOI - 10.1111/j.1440-169x.2005.00806.x
Subject(s) - sea urchin , biology , gene isoform , phospholipase c , microbiology and biotechnology , oocyte activation , biochemistry , gq alpha subunit , phosphatidylinositol , signal transduction , g protein , oocyte , gene , embryo
Calcium is a ubiquitous intracellular signaling molecule controlling a wide array of cellular processes including fertilization and egg activation. The mechanism for triggering intracellular Ca 2+ release in sea urchin eggs during fertilization is the generation of inositol‐1,4,5‐trisphosphate by phospholipase C (PLC) hydrolysis of phosphatidylinositol‐4,5‐bisphosphate. Of the five PLC isoforms identified in mammals (β, γ, δ, ∈ and ζ), only PLCγ and PLCδ have been detected in echinoderms. Here, we provide direct evidence of the presence of a PLCβ isoform, named suPLCβ, within sea urchin eggs. The coding sequence was cloned from eggs of Lytechinus pictus and determined to have the greatest degree of homology and identity with the mammalian PLCβ4. The presence of suPLCβ within the egg was verified using a specifically generated antibody. The majority of the enzyme is localized in the non‐soluble fraction, presumably the plasma membrane of the unfertilized egg. This distribution remains unchanged 1 min postfertilization. Unlike PLCβ4, suPLCβ is activated by G protein βγ subunits, and this activity is Ca 2+ ‐dependent. In contrast to all known PLCβ enzymes, suPLCβ is not activated by Gαq‐GTPγS subunit suggesting other protein regulators may be present in sea urchin eggs.