title: Effect of PKD1 gene missense mutations on polycystin-1 membrane topogenesis.
abstract: Polycystin-1 (PC1), the product of the polycystic kidney disease-1 (PKD1) gene, has a number of reported missense mutations whose pathogenicity is indeterminate. Previously, we utilized N-linked glycosylation reporter tags along with membrane insertion and topology assays to define the 11 membrane-spanning domains (I-XI) of PC1. In this report, we utilize glycosylation assays to determine whether two reported human polymorphisms/missense mutations within transmembrane (TM) domains VI and X affect the membrane topology of PC1. M3677T within TM VI had no effect on the topology of this TM domain as shown by the ability of two native N-linked glycosylation sites within the extracellular loop following TM VI to be glycosylated. In contrast, G4031D, within TM X, decreased the glycosylation of TM X reporter constructs, demonstrating that the substitution affected the C-terminal translocating activity of TM X. Furthermore, G4031D reduced the membrane association of TM X and XI together. These results suggest that G4031D affects the membrane insertion and topology of the C-terminal portion of polycystin-1 and represents a bona fide pathogenic mutation.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, KS 66160, USA.
authors.forename: Nancy M
authors.initials: NM
authors.lastname: Nims
authors.forename: Dianne
authors.initials: D
authors.lastname: Vassmer
authors.forename: Robin L
authors.initials: RL
authors.lastname: Maser
mesh_terms: D002462:Cell Membrane / Q000378:metabolism*; D006031:Glycosylation; D057809:HEK293 Cells; D006801:Humans; D020125:Mutation, Missense; D016891:Polycystic Kidney, Autosomal Dominant / Q000235:genetics*; D011110:Polymorphism, Genetic; D011487:Protein Conformation; D050396:TRPP Cation Channels / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*
chemical_list: D050396:TRPP Cation Channels