A novel phospholipase C, PLC(eta)2, is a neuron-specific isozyme.
Twelve phospholipase C (PLC) isozymes have been cloned so far, and they are divided into six classes, beta-, gamma-, delta-, epsilon-, zeta-, and eta-type, on the basis of structure and activation mechanisms. Here we report the identification of a novel PLC isozyme, PLC(eta)2. PLC(eta)2 is composed of conserved domains including pleckstrin homology, EF-hand, X and Y catalytic, and C2 domains and the isozyme-specific C-terminal region. PLC(eta)2 consists of 1164 amino acids with a molecular mass of 125 kDa. The PLC activity of PLC(eta)2 was more sensitive to calcium concentration than the PLC activity of the PLCdelta-type enzyme, which is thought to be the most calcium-sensitive PLC. Immunofluorescence analysis showed that PLC(eta)2 was localized predominantly to the plasma membrane at resting state via the pleckstrin homology domain. This observation was supported by Western blot analysis of cytosol and membrane fractions. In addition, expression of PLC(eta)2 was detected after birth and showed a restricted distribution in the brain; it was particularly abundant in the hippocampus, cerebral cortex, and olfactory bulb. The pattern was similar to that of the neuronal marker microtubule-associated protein 2 by Western blot. Furthermore, in situ hybridization showed positive signals for PLC(eta)2 in pyramidal cells of the hippocampus. Finally, we found that PLC(eta)2 was expressed abundantly in neuron-containing primary culture but not in astrocyte-enriched culture. These results indicate that PLC(eta)2 is a neuron-specific isozyme that may be important for the formation and/or maintenance of the neuronal network in the postnatal brain.
Nakahara
Masamichi
M
Laboratory of Genome and Biosignal, School of Life Science, Tokyo University of Pharmacy and Life Science, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392, Japan.
Shimozawa
Makoto
M
Nakamura
Yoshikazu
Y
Irino
Yasuhiro
Y
Morita
Mitsuhiro
M
Kudo
Yoshihisa
Y
Fukami
Kiyoko
K
D000595:Amino Acid Sequence; D000818:Animals; D001253:Astrocytes / Q000378:metabolism; D001665:Binding Sites; D001798:Blood Proteins / Q000737:chemistry; D015152:Blotting, Northern; D015153:Blotting, Western; D001921:Brain / Q000378:metabolism; D002118:Calcium / Q000737:chemistry / Q000378:metabolism; D020134:Catalytic Domain; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D017124:Conserved Sequence; D003600:Cytosol / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D016678:Genome; D006367:HeLa Cells; D006624:Hippocampus / Q000378:metabolism; D006801:Humans; D006868:Hydrolysis; D017403:In Situ Hybridization; D051379:Mice; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000737:chemistry* / Q000502:physiology*; D009474:Neurons / Q000201:enzymology*; D054801:Phosphoinositide Phospholipase C; D010750:Phosphoproteins / Q000737:chemistry; D011485:Protein Binding; D020033:Protein Isoforms; D017434:Protein Structure, Tertiary; D051381:Rats; D017386:Sequence Homology, Amino Acid; D013997:Time Factors; D014018:Tissue Distribution; D010738:Type C Phospholipases / Q000737:chemistry* / Q000502:physiology
D001798:Blood Proteins; D018076:DNA, Complementary; D009419:Nerve Tissue Proteins; D010750:Phosphoproteins; D020033:Protein Isoforms; C039077:platelet protein P47; D010738:Type C Phospholipases; D054801:Phosphoinositide Phospholipase C; C503884:Plch2 protein, mouse; D002118:Calcium