Assembly of the CD8alpha/p56(lck) protein complex in stably expressing rat epithelial cells.
We have previously characterized the biogenesis of the human CD8alpha protein expressed in rat epithelial cells. We now describe the biosynthesis, post-translational maturation and hetero-oligomeric assembly of the human CD8alpha/p56(lck) protein complex in stable transfectants obtained from the same cell line. There were no differences in the myristilation of p56(lck), or in the dimerization, O-glycosylation and transport to the plasma membrane of CD8alpha, between cells expressing either one or both proteins. In the doubly expressing cells, dimeric forms of CD8alpha established hetero-oligomeric complexes with p56(lck), as revealed by co-immunoprecipitation assays performed with anti-CD8alpha antibody. Moreover, p56(lck) bound in these hetero-oligomeric complexes was endowed with auto- and hetero-phosphorylating activity. The present study shows that: (1) the newly synthesized p56(lck) binds rapidly to CD8alpha and most of the p56(lck) is bound to CD8alpha at steady state; (2) CD8alpha/p56(lck) protein complexes are formed at internal membranes as well as at the plasma membrane; and (3) about 50% of complexed p56(lck) reaches the cell surface.
Pascale
M C
MC
Dipartimento di Scienze Farmaceutiche, Università di Salerno, Fisciano-Salerno, Italy.
Remondelli
P
P
Leone
A
A
Bonatti
S
S
D000818:Animals; D016827:CD8 Antigens / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism; D015870:Gene Expression; D006801:Humans; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck) / Q000235:genetics / Q000378:metabolism*; D009227:Myristic Acids; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D051381:Rats
D016827:CD8 Antigens; C409469:CD8 antigen, alpha chain; D009227:Myristic Acids; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck)