title: Investigating polymorphisms in membrane-associated transporter protein SLC45A2, using sucrose transporters as a model.
abstract: Solute carrier family 45 member 2 encodes the melanosomal membrane protein, membrane-associated transporter protein (MATP), of unknown function, that is required for normal melanin synthesis. The present study analyzed the effects of two human MATP mutations, D93N, which causes oculocutaneous albinism 4 (OCA4), and L374F, which is correlated with light pigmentation in European populations. Corresponding mutations were produced in the related and well-characterized sucrose transporter from rice, OsSUT1, and transport activity was measured by heterologous expression in Xenopus laevis oocytes, in addition to 14C-sucrose uptake in yeast. The mutation corresponding to D93N resulted in a complete loss of transport activity. The mutation corresponding to L374F resulted in a 90% decrease in transport activity, although the substrate affinity was unaffected. The results indicated that the D93N mutation causes OCA4 as a result of loss of MATP transport activity, and that the F374 allele confers significantly lower transport activity than L374.
authors.affiliation: Department of Plant Biology, University of Minnesota, St. Paul, MN 55108, USA.
authors.forename: Anke
authors.initials: A
authors.lastname: Reinders
authors.affiliation: Department of Plant Biology, University of Minnesota, St. Paul, MN 55108, USA.
authors.forename: John M
authors.initials: JM
authors.lastname: Ward
mesh_terms: D016115:Albinism, Oculocutaneous / Q000235:genetics* / Q000473:pathology; D000818:Animals; D000951:Antigens, Neoplasm / Q000235:genetics*; D001692:Biological Transport / Q000235:genetics*; D006801:Humans; D008543:Melanins / Q000096:biosynthesis; D026901:Membrane Transport Proteins / Q000235:genetics*; D009154:Mutation; D009865:Oocytes / Q000378:metabolism; D012275:Oryza / Q000235:genetics; D011110:Polymorphism, Genetic; D013395:Sucrose / Q000378:metabolism*; D014982:Xenopus laevis / Q000235:genetics
chemical_list: D000951:Antigens, Neoplasm; D008543:Melanins; D026901:Membrane Transport Proteins; C510061:SLC45A2 protein, human; D013395:Sucrose