The GI specific expression profile of GPR128 could possibly indicate a function in cell migration during development of GI tract endothelium. Two other genes from group II, GPR97 and GPR114, were also expressed in the GI tract but they were also detected at high levels in thymus, spleen and blood. In addition, the highest number of ESTs for these genes was detected in immune cells, spleen and bone marrow.

Altogether this indicates that GPR97 and GPR114 most probably are involved in functions of immune system in humans and rodents.All the receptors have a GPS domain in their N-terminus and long Ser/Thr-rich regions forming mucin-like stalks.