Identification and Functional Characterization of a Human GalNAc α2,6-Sialyltransferase with Altered Expression in Breast Cancer

Table 1 Acceptor substrate specificity of recombinant STM sialyltransferase

Acceptor	Representative Structures of Carbohydrates	STM	mST6GalNAc II	mST6GalNAc I
			(%)
Fetuin	NeuAcα2–3Galβ1–3GalNAc-Ser/Thr p ]NeuAcα2–3Galβ1–3(NeuAcα2–6) p ]GalNAc-Ser/Thr NeuAcα2–6(3)Galβ1–4GlcNAc-R	83.3	76.0	84.0
Asialofetuin		100.0	100.0	100.0
Asialo-agalacto-fetuin		9.12	12.0	91.0
BSM	NeuAcα2–3Galβ1–3GalNAc-Ser/Thr NeuAcα2–6GalNAc-Ser/Thr	4.73	7.32	19.0
Asialo-BSM		9.12	15.0	169.0
α 1 acid glycoprotein	NeuAcα2–6(3)Galβ1–4GlcNAc-R	0	0	14.0
Asialo-α1 acid glycoprotein		0	0	8.0
Ovomucoid		3.38	9.41	n.t.
Galβ1–3GalNAc-benzyl		0	0	0
NeuAcα2–3Galβ1–3GalNAc-benzyl		0	2.50	n.t.
Asialo-GM1	Galβ1–3GalNAcβ1–4Galβ1–4Glc1-1Cer	0	0	0
GM1b	NeuAcα2–3Galβ1–3GalNAcβ1–4Galβ1–4Glc1-1Cer	0	0	n.t.
Paragloboside	Galβ1–4GlcNAcβ1–3Galβ1–4Glc1-1Cer	0	0	n.t.

Comparison of the substrate specificity of STM (hST6GalNAc II), mST6GalNAc I (46) and mST6GAlNAc II (41) sialyltransferases. The relative activity of incorporation of sialic acids into asialofetuin as a substrate is shown. Each substrate was used at the concentration of 0.15 mM. A value of 0 indicates less than 0.1%. R represents the reminder of the N-linked oligosaccharide chain. GalNAc, N-acetylgalactosamine; GlcNAc, N-acetylglucosamine; NeuAc, N-acetylneuraminic acid.

ISSN: 1528-3658