Table 1.

Previously characterized structures of the mature, lysosomal, forms of the α and β-subunits of human Hex and the G_M2 activator protein

Protein	Initial signal peptidea	Polypeptidesb	Asn-linked glycosylationc	Disulfide bondsd
α-Subunit	M1 → A22	αp: L23 → G73e; αm: T88 → T528e	N: 114, 156, 294f	C58–C104; C277–C328; C505-C522
β-Subunit	M1 → A42	βp: A50 → G107e; βb: T122 → S311; βa: L316 → M556e	N: 84f, 142, 190, 327f	C93–C137; C309–C360; C534–C551
GM2 activator	M1 → A23	Am: S32 → I193	N: 63	C39–C183; C99–C106; C112–C138; C125–C136

^aDirects protein synthesis to the lumen of the ER and is cleaved co-translationaly.^86–89

^{b37,86,88,90–92}

^c38,92,93

^d38,94

^eThe C terminus was not well defined.

^fThese oligosaccharides are phosphorylated preferentially.