Cloning and characterization of T-cell lymphoma invasion and metastasis 2 (TIAM2), a novel guanine nucleotide exchange factor related to TIAM1.

TIAM1 is a guanine nucleotide exchange factor that was identified in a screen for genes that increase the invasiveness of T lymphoma cell lines (Habets et al., 1994, Cell 77(4): 537-549). We have identified a gene, T-cell lymphoma invasion and metastasis 2 (HGMW-approved symbol TIAM2), with significant identity to the carboxyl-terminal region of the TIAM1 and mapped it to 6q25. TIAM2 is expressed as an approximately 3.3-kb transcript in cerebrum and as an approximately 4.4-kb transcript in the cerebellum and testis. The approximately 4. 4-kb message encodes a longer form of the approximately 3.3-kb mRNA predicted protein, and both contain homology to the Dbl-homologous region (70%) and Pleckstrin-homologous (54%) regions of TIAM1. We have purified TIAM2 and shown it to have GDP-GTP exchange activity. In situ hybridizations demonstrate TIAM2 expression in the E13.5 telencephalon of mouse embryos and in the cerebral cortex, hippocampus, and ependyma of adult mouse brains.