PMID:14701816

Citation	Kouchi, Z, Fukami, K, Shikano, T, Oda, S, Nakamura, Y, Takenawa, T and Miyazaki, S (2004) Recombinant phospholipase Czeta has high Ca2+ sensitivity and induces Ca2+ oscillations in mouse eggs. J. Biol. Chem. 279:10408-12
Abstract	Sperm-specific phospholipase Czeta (PLCzeta) is known to induce intracellular Ca(2+) oscillations and subsequent early embryonic development when expressed in mouse eggs by injection of RNA encoding PLCzeta (Saunders, C. M., Larman, M. G., Parrington, J., Cox, L. J., Royse, J., Blayney, L. M., Swann, K., and Lai, F. A. (2002) Development 129, 3533-3544). The present study addressed characteristics of purified mouse PLCzeta protein that was synthesized using the baculovirus/Sf9 cell expression system. Microinjection of recombinant PLCzeta protein into mouse eggs induced serial Ca(2+) spikes quite similar to those produced by the injection of sperm extract, probably because of repetitive Ca(2+) release from the endoplasmic reticulum caused by continuously produced inositol 1,4,5-trisphosphate. Recombinant PLCdelta1 also induced Ca(2+) oscillations, but a 20-fold higher concentration was required compared with PLCzeta. In the enzymatic assay of phosphatidylinositol 4,5-bisphosphate hydrolyzing activity in vitro at various calcium ion concentrations ([Ca(2+)]), PLCzeta exhibited a significant activity at [Ca(2+)] as low as 10 nm and had 70% maximal activity at 100 nm [Ca(2+)] that is usually the basal intracellular calcium ion concentration level of cells. On the other hand, the activity of PLCdelta1 increased at a [Ca(2+)] between 1 and 30 microm. EC(50) was 52 nm for PLCzeta and 5.7 microm for PLCdelta1. Thus, PLCzeta has an approximately 100-fold higher Ca(2+) sensitivity than PLCdelta1. The ability of purified PLCzeta protein to induce Ca(2+) oscillations qualifies PLCzeta as a proper candidate of the mammalian egg-activating sperm factor. Furthermore, such a high Ca(2+) sensitivity of PLC activity as PLCzeta that can be active in cells at the resting state is thought to be an appropriate characteristic of the sperm factor, which is introduced into the ooplasm upon sperm-egg fusion, triggers Ca(2+) release first, and maintains Ca(2+) oscillations.
Links	PubMed Online version:10.1074/jbc.M313801200
Keywords	Animals; Calcium/metabolism; Cell Line; Cloning, Molecular; DNA, Complementary/metabolism; Dose-Response Relationship, Drug; Electrophoresis, Polyacrylamide Gel; Endoplasmic Reticulum/metabolism; Female; Hydrolysis; Inositol 1,4,5-Trisphosphate/metabolism; Insects; Ions; Male; Mice; Molecular Sequence Data; Oocytes/metabolism; Oscillometry; Phosphatidylinositols/metabolism; Phosphoinositide Phospholipase C; Protein Binding; Protein Structure, Tertiary; RNA/metabolism; Recombinant Proteins/chemistry; Recombinant Proteins/metabolism; Sensitivity and Specificity; Spermatozoa/metabolism; Time Factors; Type C Phospholipases/chemistry; Type C Phospholipases/metabolism
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
MOUSE:PLCZ1		GO:0004435: phosphatidylinositol phospholipase C activity	ECO:0000314:		F		Figure 4	complete CACAO 6448
MOUSE:PLCZ1	enables	GO:0004435: phosphatidylinositol phospholipase C activity	ECO:0000314: direct assay evidence used in manual assertion		F		Seeded From UniProt	complete

References

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