beta4GalT-II is a key regulator of glycosylation of the proteins involved in neuronal development.

Seven members of the human beta1,4-galactosyltransferase (beta4GalTs) have been identified and characterized by many groups. beta4GalTs play important roles in the extension of N- and O-linked glycans involved in several biological events. However, it has not been clear which beta4GalTs can act on glycoproteins, such as alpha-dystroglycan and Notch receptors, involved in neuronal development. To clarify which beta4GalTs can function, we determined the enzyme activities toward such motifs and the transcript levels in human normal tissues. Among human beta4GalTs, both beta4GalT-I and beta4GalT-II could act efficiently on all substrates, but the relative activity of beta4GalT-II was higher than that of beta4GalT-I. Transcript of beta4GalT-I was widely expressed except for brain, and on the other hand, that of beta4GalT-II was expressed at high levels in the brain. Thus, these results suggest that among human beta4GalTs, beta4GalT-II is a major regulator of the synthesis of glycans involved in neuronal development.