title: Intracellular assembly of Kell and XK blood group proteins.
abstract: Kell, a 93 kDa type II membrane glycoprotein, and XK, a 444 amino acid multi-pass membrane protein, are blood group proteins that exist as a disulfide-bonded complex on human red cells. The mechanism of Kell/XK assembly was studied in transfected COS cells co-expressing Kell and XK proteins. Time course studies combined with endonuclease-H treatment and cell fractionation showed that Kell and XK are assembled in the endoplasmic reticulum. At later times the Kell component of the complex was not cleaved by endonuclease-H, indicating N-linked oligosaccharide processing and transport of the complex to a Golgi and/or a post-Golgi cell fraction. Surface-labeling of transfected COS cells, expressing both Kell and XK, demonstrated that the Kell/XK complex travels to the plasma membrane. XK expressed in the absence of Kell was also transported to the cell surface indicating that linkage of Kell and XK is not obligatory for cell surface expression.
authors.affiliation: Lindsley F. Kimball Research Institute, The New York Blood Center, 310 East 67 Street, New York, NY, USA.
authors.forename: D
authors.initials: D
authors.lastname: Russo
authors.forename: S
authors.initials: S
authors.lastname: Lee
authors.forename: C
authors.initials: C
authors.lastname: Redman
mesh_terms: D026921:Amino Acid Transport Systems, Neutral; D000818:Animals; D000954:Antigens, Surface / Q000096:biosynthesis* / Q000235:genetics / Q000302:isolation & purification; D001692:Biological Transport; D001798:Blood Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000302:isolation & purification; D019556:COS Cells; D002352:Carrier Proteins / Q000096:biosynthesis* / Q000235:genetics; D002458:Cell Fractionation; D015180:Electrophoresis, Gel, Two-Dimensional; D004721:Endoplasmic Reticulum / Q000378:metabolism; D004910:Erythrocyte Membrane / Q000378:metabolism; D006801:Humans; D007626:Kell Blood-Group System; D017038:Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase; D008565:Membrane Proteins / Q000096:biosynthesis* / Q000235:genetics; D013997:Time Factors; D014162:Transfection
chemical_list: D026921:Amino Acid Transport Systems, Neutral; D000954:Antigens, Surface; D001798:Blood Proteins; D002352:Carrier Proteins; D007626:Kell Blood-Group System; D008565:Membrane Proteins; C087883:XK protein, human; C041106:kell-active proteins; D017038:Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase