Trypsin-sensitive and -resistant components in human T-cell membranes required for syncytium formation by human T-cell lymphotropic virus type 1-bearing cells.
Human T-cell lymphotropic virus type 1 (HTLV-1) envelope proteins play an important role in viral entry into target cells. In a syncytium formation assay consisting of a coculture of HTLV-1-bearing cells and target cells, mature gp46 and gp21 proteins each inhibited syncytium formation induced by HTLV-1-bearing cells. Experiments with 125I-labeled proteins showed that 125I-gp46 bound specifically with MOLT-4 target cells even in the presence of large amounts of gp21, whereas 125I-gp21 binding to target cells was completely blocked in the presence of large amounts of gp46. These observations suggest that HTLV-1 envelope proteins in syncytium formation interact with at least two components, which are located close to each other on the cell membrane. We isolated two components from MOLT-4 cell lysate, using Sepharose 4B columns coupled with peptides corresponding to amino acids 197 to 216 and 400 to 429, respectively, of the envelope protein. One is a trypsin digestion-sensitive component of approximately 34 to 35 kDa, which interacts specifically with gp46. The other is a nonprotein component, which interacts with gp21. This component was destroyed by sodium periodate oxidation and was partitioned into the methanol-chloroform phase. These observations suggest that these two components play an important role in HTLV-1 entry into target cells via membrane fusion.
Sagara
Y
Y
Fukuoka Red Cross Blood Center, Chikushino, Japan.
Ishida
C
C
Inoue
Y
Y
Shiraki
H
H
Maeda
Y
Y
D002462:Cell Membrane / Q000378:metabolism*; D015686:Gene Products, env / Q000378:metabolism* / Q000494:pharmacology; D015726:Giant Cells; D015368:Human T-lymphotropic virus 1 / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D008565:Membrane Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D015682:Retroviridae Proteins, Oncogenic / Q000378:metabolism* / Q000494:pharmacology; D013601:T-Lymphocytes / Q000378:metabolism* / Q000821:virology; D014357:Trypsin / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D054299:env Gene Products, Human Immunodeficiency Virus
D015686:Gene Products, env; D008565:Membrane Proteins; D015682:Retroviridae Proteins, Oncogenic; D054299:env Gene Products, Human Immunodeficiency Virus; C055265:gp21 protein, Human T-lymphotropic virus 1; C055266:gp46 protein, Human T-cell leukemia virus type I; D014357:Trypsin