Conformational and amino acid residue requirements for the saposin C neuritogenic effect

The neuritogenic effect of wild-type and mutant saposins C and A from humans and mouse expressed in Escherichia coli were studied through CD spectroscopy and a variety of genetic engineering methods. The saposins C and A are polypeptides that activate the hydrolysis of glycosphingolipids. Results indicate that wild-type saposin A has no neuritogenic effect although the reduced and alkylated forms of saposin A have. The neuritogenic effect of saposin C was reduced by as much as 60% when the conserved saposin A Tyr 30 was introduced in position 31.