Inhibition of accumulative transport by a protein from cobra venom

A heat-stable, phospholipase A-free protein from cobra venom (Naja naja) inhibits amino acid and 3-O-methyl-d-glucose transport by small intestine and the uptake of para-aminohippurate and amino acids by kidney cortex slices. Although accumulation of these substances is thought to be linked to cation concentration or movement, Na+ efflux from human erythrocytes or the inhibition of this process by ouabain is unaffected by this protein. The possibility of an effect on the Na+ pump of other tissues is not, however, ruled out.