Phospholipase amino acid sequence

Phosphoinositase C (i.e. phosphoinositide-specific phospholipase C [PLC]) enzymes are found in the vast majority of mammalian cells. Molecular cloning of these enzymes, analysis of their predicted amino acid sequences and immunological cross-reactivity indicate that at least three major forms of the enzyme exist PLC-/I, -8 and -y. Each of these enzyme types is encoded by a distinct gene. More recent experiments using the polymerase chain reaction and molecular cloning have revealed even greater enzyme di-... 

Comparison of the amino acid sequences of different isoforms of phospholipase C as well as examination of the known three-dimensional structures of phospholipase components reveal an intriguing modular stmcture (Figure 15.11). 

Hayakawa M, Horigome K, Kudo I, Tomita M, Nojima S, and Inoue K Amino acid composition and NH2-terminal amino acid sequence of rat platelet secretory phospholipase A2. J. Biocfaem. 101, 1311-1314.. 

Tsai, l.-H., Wu, S. H., and Lo, T. B. (1981). The complete amino acid sequence of the phospholipase A2 from the venom of Naja naja atra (Taiwan cobra). Toxicon 19, 141-152. 

Yoshizuini, K., Liu, S.-Y., Miyata, T., Saita, S., Ohno, M., Iwanaga, S., and Kihara, H. (1990). Purification and amino acid sequence of basic protein I, a lysine phospholipase Aa with low activity, from the venom of Trimeresurus flavoviridis (habu snake). Toxicon 28, 43-54. 

Both the normal and abnormal forms of PrP are derived from the same gene and have the same amino acid sequence. Pulse-chase studies in Sc+-MNB have demonstrated that PrP-res is in fact posttranslationally derived from mature PrP-sen (Borchelt et al., 1990 Caughey and Raymond, 1991). Unlike PrP-sen, PrP-res is resistant to phospholipases and protease treat-... 

The muscarinic cholinergic system has quite a different mode of operation in that the receptor is connected to the final action by a chain of events. Thus its response is slower than the nicotinic, where the receptor and ion channel are closely connected. Five distinct muscarinic receptors have been identified in mammals, based on anatomical location, genetic analysis, function, and amino acid sequence. All of them have seven transmembrane domains [166, 167, 168, 169]. The N- terminal domain outside the cell binds acetylcholine or other ligands at a site that includes an aspartate residue, while the C-terminal domain inside the cell is coupled to a so-called G-protein , which is initially bound to guanosine diphosphate (GDP), but exchanges it for guanosine triphosphate (GTP) when activated by its transmitter. The activated G-protein then activates phospholipase C, which hydrolyzes phosphoinositides to release 1,4,5-inositol triphosphate [170]. The final action depends on which type of cell is involved so that in some types ion channels are opened just as with the nicotinic receptor, but in other cases other processes are affected, for example the release of dopamine [171]. Since there are these differences... 

Kishimura, K, Ojima, T., Tanaka, H., Hayashi, K., and Nishita, K., 2000, Amino acid sequence of phospholipase A2 from the pyloric caeca of starfish Asterina pectinifera. Fisheries Sci., 66, 104. 

Phospholipases A (PLA ) are a diverse class of enzymes catalysing the hydrolysis of the sn-2 ester bond of phospholipids. This growing superfamily of lipolytic enzymes has at least 19 mammalian enzyme members identified to date (Balsinde et ah, 2002). The PLA enzymes have recently been systematically classified on the basis of their nucleotide and amino acid sequences (Dennis, 1997 Six and Dennis, 2000). 

Mojave toxin from Crotalus scutulatus is also structurally similar to crotoxin and is composed of two subunits (Bieber et al., 1975 Cate and Bieber, 1978). There are considerable amino acid sequence homologies between the two toxins (Aird et al., 1990). The amino acid sequence and spectroscopic properties of subunits of crotoxin are similar to other presynaptic phospholipases A from snake venoms (Aird et al., 1989a). 

The second type of presynaptic neurotoxin from a chemical viewpoint is that two polypeptide chains are connected by a disulfide bond. The most typical toxin of this type is P-btx. It consists of two chains The A chain has 120 amino acids, with a relative molecular mass (Mr) of 13,500, and the B chain has 60 amino acid residues with an of 7000. The amino acid sequence of the A chain is similar to the phospholipase A sequence and, in fact, the A chain does possess phospholipase A activity. For presynasptic activity, phospholipase A activity is essential. For instance, when Ca is replaced with Sr, phospholipase A activity and presynaptic activity are both lost. When histidine residues of the A chain are modified chemically, phospholipase A activity is lost, as well as presynasptic toxic activity. 

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