| Interacting proteins: O43173 and P13591 |
Pubmed |
SVM Score :0.0 |
| Differential biosynthesis of polysialic acid on neural cell adhesion molecule ( NCAM ) and oligosaccharide acceptors by three distinct alpha 2 , 8 sialyltransferases , ST8Sia 4 ( PST ) , ST8Sia 2 ( STX ) , and ST8Sia 3 . ^^^ Polysialylation of NCAM was shown to be achieved by two alpha 2 , 8 polysialyltransferases , ST8Sia 4 ( PST ) and ST8Sia 2 ( STX ) , which are moderately related to another alpha 2 , 8 sialyltransferase , ST8Sia 3 . ^^^ First , we found that ST8Sia 3 can form polysialic acid on the enzyme itself ( autopolysialylation ) but not on NCAM . ^^^ By using a newly established method , we found that ST8Sia 4 , ST8Sia 2 , and ST8Sia 3 all add oligosialic and polysialic acid on various sialylated N acetyllactosaminyl oligosaccharides , including NCAM N glycans , fetuin N glycans , synthetic sialylated N acetyllactosamines , and on alpha ( 2 ) HS glycoprotein . ^^^ Moreover , ST8Sia 4 and ST8Sia 2 catalyze polysialylation of NCAM much more efficiently than ST8Sia 3 . ^^^ |
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| Interacting proteins: O43173 and P13591 |
Pubmed |
SVM Score :0.0 |
| These results suggested that both ST8Sia 2 and 4 catalyze polySia synthesis toward preferred acceptor substrates such as NCAM , whereas they mainly catalyze disialylation , similarly to ST8Sia 3 , toward unfavorable substrates such as enzyme themselves . . ^^^ |
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| Interacting proteins: O43173 and P13591 |
Pubmed |
SVM Score :0.0 |
| By contrast , ST8Sia 3 , which is moderately homologous to ST8Sia 2 and ST8Sia 4 , adds oligosialic acid to itself but very inefficiently to NCAM . ^^^ Here , we report domains of polysialyltransferases required for NCAM recognition and polysialylation by generating chimeric enzymes between ST8Sia 4 and ST8Sia 3 or ST8Sia 2 . ^^^ To identify domains responsible for NCAM polysialylation , different segments of the ST8Sia 4 catalytic domain , identified by the deletion experiments , were replaced with corresponding segments of ST8Sia 2 and ST8Sia 3 . ^^^ However , chimeric enzymes that contain only the carboxyl terminal segment of ST8Sia 4 and the amino terminal segment of ST8Sia 3 showed very weak activity toward NCAM , even though they had strong activity in polysialylating themselves . ^^^ In fact , chimeric enzymes containing the amino terminal portion of ST8Sia 4 fused to downstream sequences of ST8Sia 3 inhibited NCAM polysialylation in vitro , although they did not polysialylate NCAM . ^^^ |
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