title: MHC class I-like MILL molecules are beta2-microglobulin-associated, GPI-anchored glycoproteins that do not require TAP for cell surface expression.
abstract: MILL (MHC class I-like located near the leukocyte receptor complex) is a family of MHC class I-like molecules encoded outside the MHC, which displays the highest sequence similarity to human MICA/B molecules among known class I molecules. In the present study, we show that the two members of the mouse MILL family, MILL1 and MILL2, are GPI-anchored glycoproteins associated with beta2-microglobulin (beta2m) and that cell surface expression of MILL1 or MILL2 does not require functional TAP molecules. MILL1 and MILL2 molecules expressed in bacteria could be refolded in the presence of beta2m, without adding any peptides. Hence, neither MILL1 nor MILL2 is likely to be involved in the presentation of peptides. Immunohistochemical analysis revealed that MILL1 is expressed in a subpopulation of thymic medullary epithelial cells and a restricted region of inner root sheaths in hair follicles. The present study provides additional evidence that MILL is a class I family distinct from MICA/B.
authors.affiliation: Department of Biosystems Science, School of Advanced Sciences, Graduate University for Advanced Studies (Sokendai), Hayama, Japan.
authors.forename: Mizuho
authors.initials: M
authors.lastname: Kajikawa
authors.forename: Tomohisa
authors.initials: T
authors.lastname: Baba
authors.forename: Utano
authors.initials: U
authors.lastname: Tomaru
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Watanabe
authors.forename: Satoru
authors.initials: S
authors.lastname: Koganei
authors.forename: Sachiyo
authors.initials: S
authors.lastname: Tsuji-Kawahara
authors.forename: Naoki
authors.initials: N
authors.lastname: Matsumoto
authors.forename: Kazuo
authors.initials: K
authors.lastname: Yamamoto
authors.forename: Masaaki
authors.initials: M
authors.lastname: Miyazawa
authors.forename: Katsumi
authors.initials: K
authors.lastname: Maenaka
authors.forename: Akihiro
authors.initials: A
authors.lastname: Ishizu
authors.forename: Masanori
authors.initials: M
authors.lastname: Kasahara
mesh_terms: D000818:Animals; D000950:Antigens, Ly / Q000378:metabolism; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism*; D002469:Cell Separation; D004847:Epithelial Cells / Q000378:metabolism; D006023:Glycoproteins / Q000378:metabolism*; D018859:Hair Follicle / Q000378:metabolism; D015395:Histocompatibility Antigens Class I / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D011485:Protein Binding; D017510:Protein Folding; D011817:Rabbits; D013950:Thymus Gland / Q000378:metabolism; D001613:beta 2-Microglobulin / Q000378:metabolism*
chemical_list: D000950:Antigens, Ly; D006023:Glycoproteins; D015395:Histocompatibility Antigens Class I; C074650:Ly6a protein, mouse; D008565:Membrane Proteins; D001613:beta 2-Microglobulin