We are investigating the consequences of mitogen mediated signals to T cells by isolating and characterizing genes that constitute the immediate early transcriptional response to these events. Primary sequence analysis has revealed that 3 early induced genes code for membrane associated proteins. Activation-induced changes in cell surface proteins resulting from a primary stimulus play a particularly important role in regulating downstream proliferative and differentiative responses. Important events mediated at the cell surface include the binding of soluble factors and interactions with other cells and extracellular matrix. 237 encodes a hematopoietic cell-specific, 23 kDalton type 2 membrane surface protein. 237 belongs to the C-type lectin superfamily of proteins. Other known C- type lectins on lymphoid cells are signal-transducing molecules. 237 is unique in that its expression is induced in activated cells. 276 encodes a surface protein that contains 7 membrane-spanning regions characteristic of signal-transducing receptors that couple to G proteins. 276 also contains at the amino terminus, EGF repeats that are thought to be involved in protein-protein interactions, and thus are often found on receptors or their ligands. 154 encodes a 158 amino acid peptide that contains a hydrophobic leader sequence and no other putative transmembrane region. 154 does not appear to be secreted but is membrane-associated, possibly predominantly with the endoplasmic reticulum.
