Cloning of a phospholipase C-delta 1 of rabbit skeletal muscle.
The phospholipase C isoform responsible for the increase in the total myoplasmic inositol 1,4,5-trisphosphate concentration during tetanic contraction of isolated skeletal muscle and its mechanism of activation is not known. We have cloned and sequenced a phospholipase C cDNA of rabbit skeletal muscle coding for a protein of 745 amino acids with a molecular mass of 84,440 kDa. The deduced amino acid sequence exhibits the phospholipase C-specific domains X and Y which according to current knowledge very likely represent the catalytic centre of the enzyme. An overall sequence homology of 88% to the phospholipase C-delta 1 of rat brain suggests that the encoded protein represents a phospholipase C-delta 1 isoform of rabbit skeletal muscle. Northern blot analysis shows, that this phospholipase C-delta is dominantly expressed in skeletal muscle, less strongly in smooth muscle (uterus) and lung and weakly in heart, kidney and brain. In the N-terminal part of the primary structure a consensus sequence for a canonical EF-hand Ca2+ binding domain can be identified together with a short positively charged motif which recently has been suggested to be essential for the binding of phosphatidylinositol 4,5-bisphosphate. If these two domains which are unique for phospholipase C-delta are sufficient in establishing a mechanism for the activation of the enzyme, inositol 1,4,5-trisphosphate formation in skeletal muscle could be the consequence of an increase in myoplasmic Ca2+.
Milting
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Institut für Physiologische Chemie, Abteilung für Biochemie Supramolekularer Systeme, Ruhr-Universität, Bochum, Germany.
Heilmeyer
L M
LM
Thieleczek
R
R
D000595:Amino Acid Sequence; D000818:Animals; D015152:Blotting, Northern; D001921:Brain / Q000201:enzymology; D003001:Cloning, Molecular; D017124:Conserved Sequence; D005260:Female; D007527:Isoenzymes / Q000096:biosynthesis* / Q000737:chemistry*; D008969:Molecular Sequence Data; D018482:Muscle, Skeletal / Q000201:enzymology*; D009928:Organ Specificity; D054803:Phospholipase C delta; D012333:RNA, Messenger / Q000096:biosynthesis; D011817:Rabbits; D051381:Rats; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry; D017386:Sequence Homology, Amino Acid; D010738:Type C Phospholipases / Q000096:biosynthesis* / Q000737:chemistry*
D007527:Isoenzymes; D012333:RNA, Messenger; D011994:Recombinant Proteins; D010738:Type C Phospholipases; D054803:Phospholipase C delta