A new member of the alpha4-related molecule (alpha4-b) that binds to the protein phosphatase 2A is expressed selectively in the brain and testis.

A murine alpha4, identified in lymphocytes, binds to protein phosphatase 2A (PP2A). We found another murine alpha4-related gene (named alpha4-b) expressed selectively in the brain and testis. The alpha4-b transcript is expressed in the brain and testis, but is not detected in the spleen, thymus, bone marrow, liver, kidney, lung, heart or muscle. In-situ RNA hybridization analysis suggested that alpha4-b is expressed in most neuronal cells in the brain, but it is not expressed in the glial cells. The alpha4-b cDNA encodes a putative protein that is highly homologous (66% identity in amino-acid sequence) to the alpha4 molecule. The alpha4-b protein associates with the catalytic subunit of PP2A (PP2Ac), suggesting that the alpha4-b protein is involved in the regulation of phosphatase activity in neuronal cells.