A lymphocyte cell surface heat shock protein homologous to the endoplasmic reticulum chaperone, immunoglobulin heavy chain binding protein BIP.
BE2 is a cell surface monomeric 78-kDa protein (BE2-78) expressed on the malignant lymphocytes of cutaneous T-cell lymphoma and adult T-cell leukemia, on some lymphocytes from patients with acquired immunodeficiency syndrome and on Epstein-Barr virus-transformed B cells. BE2-78 positivity of cutaneous T-cell lymphoma tumor cells is a useful diagnostic and prognostic determinant in evaluating patients with that disorder. The BE2-78 protein was isolated from Epstein Barr virus-transformed B cells, purified by 1- and 2-dimensional electrophoresis and then sequenced. The sequence of 4 isolated peptide fragments was highly homologous with the 78-kDa heat shock protein, BiP, an endoplasmic reticulum chaperone. The similarity between BiP and BE2-78 was supported by the demonstration that BE2-78, like BiP, avidly binds to ATP. However, polyclonal and monoclonal reagents that recognize cytoplasmic 70- and 78-kDa heat shock proteins do not detect the BE2-78 antigen on the cell surface of cutaneous T-cell lymphoma or Epstein Barr virus-transformed lymphocytes, and peptide mapping demonstrates sequence divergence, suggesting that either they are distinct or conformationally different molecules. Our results indicate that BE2-78 is a cell surface heat shock protein. The possibility that malignant or transformed lymphocytes may express cell surface molecules with the capacity to bind a spectrum of exogenous or endogenous peptides has potential implications for tumor immunology.
Berger
C L
CL
Department of Dermatology, Yale University, School of Medicine, New Haven, CT 06510-8059, USA. BergerCL@MASPO1.MAS.YALE.EDU
Dong
Z
Z
Hanlon
D
D
Bisaccia
E
E
Edelson
R L
RL
D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D000954:Antigens, Surface / Q000737:chemistry* / Q000378:metabolism; D015153:Blotting, Western; D002352:Carrier Proteins / Q000737:chemistry* / Q000378:metabolism; D002460:Cell Line; D002462:Cell Membrane / Q000737:chemistry; D000091342:Endoplasmic Reticulum Chaperone BiP; D006360:Heat-Shock Proteins / Q000737:chemistry* / Q000378:metabolism; D007525:Isoelectric Focusing; D018832:Molecular Chaperones / Q000737:chemistry* / Q000378:metabolism; D008969:Molecular Sequence Data; D011485:Protein Binding; D017386:Sequence Homology, Amino Acid
D000954:Antigens, Surface; D002352:Carrier Proteins; D000091342:Endoplasmic Reticulum Chaperone BiP; D006360:Heat-Shock Proteins; D018832:Molecular Chaperones; D000255:Adenosine Triphosphate