Mouse MD-1, a molecule that is physically associated with RP105 and positively regulates its expression.
RP105 is a leucine-rich repeat molecule that is expressed on mouse B cells and transmits a growth-promoting signal. An anti-RP105 Ab precipitated additional molecules as well as RP105. These molecules were found to be a mouse homologue of chicken MD-1. Chicken MD-1 was previously isolated as a v-myb-regulated gene, since its transcription increases rapidly after v-myb induction. Mouse MD-1, when transiently expressed as an epitope-tagged protein, is secreted in culture fluid but tethered to the cell surface by coexpressed RP105. An association of these molecules was confirmed by immunoprecipitation with the anti-RP105 Ab and subsequent probing of the epitope tag on MD-1. Moreover, MD-1 has an effect on the expression of RP105. In transient transfection of RP105, the percentage of RP105-positive cells increased more than twice with the coexpression of MD-1. The stable expression of MD-1 conferred approximately a sevenfold increase in cell surface RP105 on a cell line that expresses RP105 alone. Thus, MD-1 is physically associated with RP105 and is important for efficient cell surface expression.
Department of Immunology, Saga Medical School, Japan. miyake@post.saga-med.ac.jp
K
K
Miyake
R
R
Shimazu
J
J
Kondo
T
T
Niki
S
S
Akashi
H
H
Ogata
Y
Y
Yamashita
Y
Y
Miura
M
M
Kimoto
D000595:Amino Acid Sequence; D000818:Animals; D015703:Antigens, CD; D000954:Antigens, Surface / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D001483:Base Sequence; D002460:Cell Line; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000302:isolation & purification; D007668:Kidney; D000090263:Leucine-Rich Repeat Proteins; D008562:Membrane Glycoproteins; D008565:Membrane Proteins / Q000096:biosynthesis* / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D008970:Molecular Weight; D011233:Precipitin Tests; D011485:Protein Binding; D011506:Proteins / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
D015703:Antigens, CD; D000954:Antigens, Surface; D018076:DNA, Complementary; D000090263:Leucine-Rich Repeat Proteins; C490500:Ly78 protein, mouse; C113553:Ly86 protein, mouse; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D011506:Proteins