Endogenous activator of intestinal guanylate cyclase. It stimulates this enzyme through the same receptor binding region as the heat-stable enterotoxins. May be a potent physiological regulator of intestinal fluid and electrolyte transport. May be an autocrine/paracrine regulator of intestinal salt and water transport. GUCA2B Protein, Human, Recombinant (His) is expressed in HEK293 mammalian cells with N-6xHis tag. The predicted molecular weight is 13.5 kDa and the accession number is Q16661.