Nature 252, 602 - 604 (13 December 1974); doi:10.1038/252602a0

Immunoglobulin of T lymphoma cells is an integral membrane protein

DIETER HAUSTEIN^†, JOHN. J. MARCHALONIS^† & MICHAEL J. CRUMPTON^*

^†The Walter and Eliza Hall Institute of Medical Research, P.O. Royal Melbourne Hospital, Victoria 3050
The John Curtin School of Medical Research, Australian National University, Canberra, Australia
^*Permanent address: National Institute of Medical Research, Mill Hill, London NW7, UK.

IMMUNOGLOBULINS, predominantly 7S IgM molecules (molecular weight 200,000), are associated with the plasma membranes of lymphocytes¹⁻³ and considerable evidence suggests that these proteins function as receptors for antigen⁴⁻⁶. If these molecules are themselves integral parts of the lymphocyte membrane or are strongly associated with integral proteins they may transmit antigen-induced signals through the membrane and initiate cell activation. It has been proposed that the antigen-combining site of T cell IgM protrudes from the cell surface, but that the Fc portion bearing the characteristic antigenic determinants of the heavy chain is not accessible to large molecules in the solvent^2,7. If these proposals are correct, then surface immunoglobulin of T cells might be considered an integral constituent of the plasma membrane⁸.

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