Signal transduction by ClassI MHC

Ian A. York york at
Fri Sep 22 14:43:17 EST 1995

In article <43tij7$hon at>,
Janet Kelso <kelso at> wrote:
>I was wondering if any research has been done on whether or not the 50
>kilodalton cytoplasmic domain of the class I MHC plays a role in signal
>transduction. If so, what is the outcome of the signal?

Just to make sure ... the cytoplasmic region is not 50 kDa, the whole 
heavy chain is about 50 kDa (more like 45 kDa including carbohydrates).  
The cytoplasmic region is only about (mumble) ... well, it's smaller.  

A few people have looked at the possibility of MHC I transducing signals,
and it's quite possible that it does happen.  The function of this
signalling is not known.  Dasgupta suggests that on T cells MHC I signal;s
enhance the T cell activation through reducing CD3 downregulation, and may
have other functions as well.  I don't know that a very convincing answer 
has been given.

A number of MHC I molecules are also phosphorylated.  The reason for this 
is even more mysterious.  MHC I signal transduction is probably not the 
(sole?) reason for this, as the molecules are phosphorylated quite 
early, I think - but who knows?

Skov, S.  Odum, N.  Claesson, M.H. 
MHC class I signaling in T cells leads to tyrosine kinase activity and
PLC-gamma 1 phosphorylation. 
J. Immunol. 154:1167-1176 (1995)

Dasgupta, J.D.  Granja, C.B.  Yunis, E.J.  Relias, V. 
MHC class I antigens regulate CD3-induced tyrosine phosphorylation of 
proteins in T cells.
Int. Immunol. 6(3):481-489 (1994)

Dasgupta JD.  Egea E.  Relias V.  Iglesias A.  Gladstone P.  Yunis EJ.
Involvement of major histocompatibility complex class I antigens in T 
cell activation.
European Journal of Immunology.  20(7):1553-61 (1990)
Ian York   (york at
Dana-Farber Cancer Institute, 44 Binney St., Boston MA 02115
Phone (617)-632-3921     Fax  (617)-632-2627

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