       Document 0697
 DOCN  M9640697
 TI    Calreticulin interacts with newly synthesized human immunodeficiency
       virus type 1 envelope glycoprotein, suggesting a chaperone function
       similar to that of calnexin.
 DT    9604
 AU    Otteken A; Moss B; Laboratory of Viral Diseases, NIAID, National
       Institutes of; Health, Bethesda, Maryland 20892, USA.
 SO    J Biol Chem. 1996 Jan 5;271(1):97-103. Unique Identifier : AIDSLINE
       MED/96132888
 AB    The ubiquitous eukaryotic protein calreticulin has been detected in a
       wide variety of different cell types. Recently, calreticulin was found
       to bind in vitro to a number of proteins isolated from the endoplasmic
       reticulum. In addition, calreticulin has sequence similarities with the
       molecular chaperone calnexin. These data suggest that calreticulin might
       also act as a chaperone. We found that calreticulin associated
       transiently with a large number of newly synthesized cellular proteins.
       In cells expressing recombinant human immunodeficiency virus (HIV)
       envelope glycoprotein, gp160 bound transiently to calreticulin with a
       peak at 10 min after its synthesis. Binding of gp120 to calreticulin was
       not detected because proteolytic cleavage of gp160 occurs in the
       trans-Golgi. Nonglycosylated HIV envelope protein was not associated
       with calreticulin, suggesting a requirement for N-linked
       oligosaccharides on newly synthesized proteins as has been reported for
       calnexin. The in vivo binding kinetics of calnexin and calreticulin to
       gp160 were very similar. Sequential immunoprecipitations provided
       evidence for the existence of ternary complexes of gp160, calreticulin,
       and calnexin. The data suggested that most of the gp160 associated with
       calreticulin was also bound to calnexin but that only a portion of the
       gp160 associated with calnexin was also bound to calreticulin.
 DE    Adenosine Triphosphate/METABOLISM  Calcium-Binding Proteins/*METABOLISM
       Chaperonins/*METABOLISM  Gene Products, env/*METABOLISM  Glycosylation
       HIV-1/*METABOLISM  Kinetics  Protein Binding  Protein
       Precursors/*METABOLISM  Protein Processing, Post-Translational
       Ribonucleoproteins/METABOLISM  Support, Non-U.S. Gov't
       Tunicamycin/PHARMACOLOGY  JOURNAL ARTICLE

       SOURCE: National Library of Medicine.  NOTICE: This material may be
       protected by Copyright Law (Title 17, U.S.Code).

