title: Biochemical identification of I-J as a novel dimeric surface molecule on mouse helper and suppressor T cell clones.
abstract: A monoclonal anti-I-Jk antibody JK10-23 was capable of precipitating the putative I-Jk molecule from NP-40 lysates of 125I-surface labelled mouse T cell clones with either helper or suppressor functions. The I-J molecule detected by specific immunoprecipitation and subsequent one- or two-dimensional gel analysis was a Mr 84-90 K dimer composed of 42-46 K glycopeptide subunits having isoelectric point pH 5.3 to 6.4. A monomeric form of I-J also existed in some of the T cell clones. The I-J subunit was a glycosylated polypeptide with a 41 K backbone having at least two glycosylation sites. I-J was distinguishable from other known dimeric T cell surface molecules with comparable molecular size, that is, T cell receptor alpha beta heterodimer, A1 and YE molecules expressed on a T cell leukemia EL4, and mouse CD28. The I-Jk molecule was precipitable from T cell clones with I-Ak and I-Ek restriction specificities including a clone derived from an H-2b----H-2bxkF1 radiation bone marrow chimera. None of the H-2b-restricted T cell clones from H-2b and its F1 showed the I-Jk immunoreactivity. T cell clones having either I-Ab or I-Ek restriction specificities derived from intra-H-2 recombinant mouse B10.A(5R) were positive for the I-Jk, while an I-Ab-restricted T cell clone from B10.A(3R) was negative in the I-Jk immunoprecipitation. The results indicate that I-J is a novel dimeric surface molecule, most likely to be a homodimer, expressed on T cells according to the major histocompatibility complex.
authors.affiliation: Department of Immunology, Faculty of Medicine, University of Tokyo, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Nakayama
authors.forename: R T
authors.initials: RT
authors.lastname: Kubo
authors.forename: H
authors.initials: H
authors.lastname: Kishimoto
authors.forename: Y
authors.initials: Y
authors.lastname: Asano
authors.forename: T
authors.initials: T
authors.lastname: Tada
mesh_terms: D000118:Acetylglucosaminidase; D000818:Animals; D002999:Clone Cells / Q000276:immunology; D015180:Electrophoresis, Gel, Two-Dimensional; D000949:Histocompatibility Antigens Class II / Q000737:chemistry* / Q000302:isolation & purification; D017038:Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase; D051379:Mice; D008968:Molecular Conformation; D013045:Species Specificity; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology*; D050378:T-Lymphocytes, Regulatory / Q000276:immunology*
chemical_list: D000949:Histocompatibility Antigens Class II; C043911:I-J-antigen; D000118:Acetylglucosaminidase; D017038:Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase