Cell surface expression of immature H glycoprotein in measles virus-infected cells.
Two forms of hemagglutinin (H) protein, one with an apparent molecular mass of 78 kDa (78K H protein) and the other with that of 74 kDa (74K H protein), are present in cells infected with measles virus (MV). We previously observed that only the mature 78K H protein, a completely glycosylated form of the 74K H protein, was expressed on the cell surface of the infected cells. In the present study, we detected transient expression of the 74K H protein on the cell surface of infected cells by pulse-chase studies, although the level of this expression was much lower than that of the 78K H protein. On the cell surface the 74K H protein was present as dimers and sensitive to endo-beta-N-acetylglucosaminidase H digestion. Treatment with brefeldin A, which blocks the transport of membrane and secretory proteins from the endoplasmic reticulum to the Golgi apparatus, inhibited the cell surface expression of the 78K H protein, but not that of the 74K H protein. These data suggest that a part of the MV 74K H proteins could be transported directly to the cell surface - probably via an alternative pathway - without processing to the complex form in the Golgi apparatus.
Ogura
H
H
Department of Virology, Osaka City University Medical School, Asahimachi 1-4-3, Abeno-ku, Osaka, Japan. ogurah@med.osaka-cu.ac.jp
Matsunaga
I
I
Takano
Y
Y
Ning
X
X
Ayata
M
M
Tanaka
K
K
Seto
T
T
Furukawa
K
K
Ito
N
N
Shingai
M
M
Kimura
T
T
Ichihara
K
K
Kubo
H
H
Murakami
T
T
D000818:Animals; D020126:Brefeldin A / Q000494:pharmacology; D019556:COS Cells; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002522:Chlorocebus aethiops; D006388:Hemagglutinins / Q000032:analysis / Q000378:metabolism*; D006801:Humans; D015151:Immunoblotting; D008459:Measles virus / Q000378:metabolism*; D020033:Protein Isoforms / Q000378:metabolism; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D014709:Vero Cells
D006388:Hemagglutinins; D020033:Protein Isoforms; D011500:Protein Synthesis Inhibitors; D020126:Brefeldin A