Pg is an important mediator of angiostatin production in the fibrinolytic pathway. Pg is made up of five subunit kringle molecules (Pg-K1 to Pg-K5), of which the first three make the protein angiostatin. VEK-30 is a domain of the group A streptococcal protein PAM. It binds to Pg-K2 of angiostatin and activates the molecule to mediate its anti-angiogenic effects. VEK-30 binds to angiostatin via a C terminal lysine with argininyl and glutamyl side chain residues known as a 'through space isostere'.