Endocrine cells in pancreatic islets of Langerhans are immunoreactive to antibody against guanine nucleotide-binding protein (Go) purified from rat brain.

Guanine nucleotide-binding proteins (G proteins) are usually classified into four subclasses (Gs, Gi, Go and Gt or transducin). We localized the anti-Go immunoreactivities in islets of Langerhans of the rat pancreas by using affinity-purified antibody against the alpha-subunit of Go purified from rat brain. Endocrine cells of the islets of Langerhans were stained with this Go antibody, but the acinar cells in the exocrine portion of the pancreas were immunonegative to this antibody. These findings strongly suggest that Go protein functions as intermediaries in the transmembrane signalling pathway in the endocrine cells of the islets of Langerhans.