Defective GALNT12 causes CRCS1

The family of UDP GalNAc:polypeptide N acetylgalactosaminyltransferases (GalNAc transferases, GALNTs) carry out the addition of N acetylgalactosamine on serine, threonine or possibly tyrosine residues on a wide variety of proteins, and most commonly associated with mucins (Wandall et al. 1997). This reaction takes place in the Golgi apparatus (Rottger et al. 1998). There are 20 known members of the GALNT family, 15 of which have been characterised and 5 candidate members which are thought to belong to this family based on sequence similarity (Bennett et al. 2012). The GALNT-family is classified as belonging to CAZy family GT27. Defects in one of the GALNT family, GALNT12 (Guo et al. 2002) (MIM: 610290) can result in decreased glycosylation of mucins, mainly expressed in the digestive organs such as the stomach, small intestine and colon, and may play a role in colorectal cancer 1 (CRCS1; MIM:608812). CRCS1 is a complex disease characterised by malignant lesions arising from the inner walls of the colon and rectum (Guda et al. 2009, Clarke et al. 2012).

UDP-半乳糖胺:多肽N-乙酰半乳糖胺基转移酶家族（GalNAc转移酶，GALNTs）负责在多种蛋白质的丝氨酸、苏氨酸或可能酪氨酸残基上添加N-乙酰半乳糖胺，此过程与粘蛋白密切相关（Wandall等人，1997年）。该反应发生在高尔基体中（Rottger等人，1998年）。GALNT家族已知有20个成员，其中15个已被鉴定，5个候选成员根据序列相似性被认为属于该家族（Bennett等人，2012年）。GALNT家族被归类为CAZy家族GT27。GALNT家族中某一成员的缺陷，如GALNT12（Guo等人，2002年）（MIM: 610290），可能导致粘蛋白糖基化减少，主要表达于消化器官如胃、小肠和结肠，可能参与结直肠癌1（CRCS1；MIM:608812）的发生。CRCS1是一种复杂的疾病，其特征为结肠和直肠内壁发生恶性病变（Guda等人，2009年，Clarke等人，2012年）。