Tissue distribution and subcellular localization of a variant form of the human ST2 gene product, ST2V

The human ST2 gene has been known to encode three splice variants; namely, a soluble secreted form of ST2, a transmembrane form of ST2L, and ST2V of u ndetermined localization. Therefore, analysis of tissue distribution and su bcellular localization of ST2V is important to elucidate functional relatio nships among the three splice variants of the human ST2 gene. RT-PCR proced ure revealed that ST2V is predominantly expressed in the stomach, small int estine, and colon. Transfection of ST2V cDNA into COS7 cells in the presenc e of [S-35] methionine and cystein produced radiolabeled 40 kDa protein, wh ich is recognized by specific monoclonal antibody against human ST2. Subcel lular fractionation analysis showed that ST2V protein was distributed in th e insoluble fraction of the cell lysate. Finally, ST2V protein was detected on the plasma membrane of COS7 cells, which had been transfected with ST2V cDNA, by confocal laser microscopic analysis. These findings taken togethe r, indicate that ST2V protein localizes on the plasma membrane, suggesting its possible role in modification of the ST2L-signaling pathways. (C) 2001 Academic Press.