G Protein Signaling Modulator 1 (GPSM1)

The deduced Ags3-long protein contains 7 tetratricopeptide (TPR) repeats in its N-terminal half and 4 G protein regulatory motifs in its C-terminal half. The 2 Ags3-short proteins lack the TPRs, but they contain 3 complete G protein regulatory motifs and part of the fourth motif found in Ags3-long. Northern blot analysis of human tissues detected a 4.0-kb transcript that was highly expressed in heart and brain. A 2.0-kb transcript was also enriched in adult heart, whereas fetal heart expressed predominantly the 4.0-kb variant. Rat Ags3-short was distributed throughout transfected COS-7 and Chinese hamster ovary cells, and Ags3-long exhibited a more punctate cytoplasmic distribution. Mutation analysis indicated that the presence or absence of TPR repeats accounted for the differences in intracellular targeting of Ags3-long and -short.