Stage- and tissue-specific expression of a beta-1,4-galactosyltransferase in the embryonic epidermis

Changes in oligosaccharide structures of glycoconjugates have been observed , and are postulated to have key roles in embryonic development and differe ntiation. N-Acetylglucosamine (GlcNAc) beta -1,4-galactosyltransferase (bet a 4GalT) AKI showed different expression patterns in time and space, and di fferent enzymatic activity from the other known family members, The epiderm is of mouse embryo included a high level of AKI activities. which transferr ed galactose (Gal) to endogenous glycoprotein (molecular weight 130 kDa) (G P130). The maximum activity was for 13.5-d postcoitum embryos. Specific ant ibody against AKI inhibited 81% of GlcNAc beta 4GalT activities, which indi cates that AKI represents the major part of the embryonic epidermis enzymes . AKI shows 2.2 times higher galactosyltransferase activity toward Gal-acce ptor glucose with alpha -lactalbumin (alpha -LA) than toward GlcNAc without alpha -LA. AKI is also expressed in mouse melanoma and leukemia cell lines and in human basal cell carcinoma specimens. The GP130 Gal acceptor once g alactosylated by AKI may be directly involved in epidermal differentiation and oncogenesis.