ST8Sia-II (STX) belongs to a family of α2-8-sialyltransferases, and exhibits polysialic acid synthase activity like ST8Sia-IV (see Chap. 48). The cDNAs encoding ST8Sia-II have been cloned from rat (Livingston and Paulson 1993), mouse (Kojima et al. 1995a), human (Scheidegger et al. 1995; Angata et al. 1997), and Xenopus (Kudo et al. 1998). The deduced amino acid sequences of the ST8Sia-II cloned from human, mouse, and rat exhibit the same 375 amino acid lengths, and conserve over 99% among them. The amino acid sequence of ST8Sia-II cloned from mouse showed 34.4% and 56.0% identity with mouse ST8Sia-III and mouse ST8Sia-IV, respectively, but no similarity of the amino acid sequence (less than 30%) of mouse ST8Sia-II was observed toward those of other sialyltransferases cloned from mouse. Like other sialyltransferases, ST8Sia- II exhibits type II membrane protein topology and has characteristic motifs for sialvltransferases called sialvlmotifs L, S, and VS.
KeywordsSialic Acid Deduce Amino Acid Sequence Neural Cell Adhesion Molecule Neuro2a Cell Sialic Acid Residue
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