Defective SLC35A2 does not exchange UDP-Gal, UDP-GalNAc for UMP

Stable Identifier
Reaction [transition]
Homo sapiens
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The human gene SLC35A2 encodes the UDP-galactose transporter. It is located on the Golgi membrane and mediates the antiport of UDP-Gal into the Golgi lumen in exchange for UMP. Nucleotide sugars such as UDP-Gal are used in protein glycosylation in the Golgi lumen. This transporter is also known to transport UDP-N-acetylgalactosamine (UDP-GalNAc) by the same antiport mechanism. Defects in SLC35A2 limit Golgi-localised pools of UDP-Gal, resulting in truncated beta-GlcNAc-terminated N-glycans and alpha-GalNAc-terminated O-glycans. Defects in SLC35A2 can cause congenital disorder of glycosylation 2M (CDG2M; MIM:300896), a disorder characterised by developmental delay, hypotonia, ocular defects and brain malformations. Congenital disorders of glycosylation (CDGs) are generally characterised by under-glycosylated serum glycoproteins and a wide spectrum of clinical features. Mutations in SLC25A2 causing CDG2M are G8Sfs*9, V331I and M1? (Ng et al. 2013). Defects in SLC35A2 can also cause early infantile epileptic encephalopathy 22 (EIEE22; MIM:300896), a severe form of epilepsy characterised by by frequent tonic seizures or spasms beginning in infancy and accompanied by developmental problems. Mutations in SLC35A2 causing EIEE22 are Y145Pfs*76 and F324Lfs*25 (Kodera et al. 2013).

Literature References
PubMed ID Title Journal Year
23561849 Mosaicism of the UDP-galactose transporter SLC35A2 causes a congenital disorder of glycosylation

Chong, JX, Raymond, K, Bamshad, MJ, Gilbert, RD, He, M, Li, C, Kozenko, M, Ng, BG, Nickerson, DA, Turner, EH, Kircher, M, Losfeld, ME, Smith, JD, Buckingham, KJ, Shendure, J, Szybowska, M, Patterson, MC, Eroshkin, A

Am. J. Hum. Genet. 2013
24115232 De novo mutations in SLC35A2 encoding a UDP-galactose transporter cause early-onset epileptic encephalopathy

Miyake, N, Nishiyama, K, Saitsu, H, Osaka, H, Wada, Y, Tsurusaki, Y, Kondo, Y, Haginoya, K, Sugahara, K, Matsumoto, N, Mizumoto, S, Nakamura, K, Yuasa, I, Nakashima, M, Iai, M, Kodera, H, Hayasaka, K, Maegaki, Y, Okamoto, N, Kato, M

Hum. Mutat. 2013
Catalyst Activity

UDP-galactose transmembrane transporter activity of SLC35A2 mutants [Golgi membrane]

Normal reaction
Functional status

Loss of function of SLC35A2 mutants [Golgi membrane]

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