The peptide is a synthetic inhibitor of the cGKI protein kinase. The sequence corresponds to the mutated S32A phosphorylation site analog within residues 29-35 of human histone H2B. The cGKI kinase belongs to the AGC Ser/Thr family, cGMP subfamily, and has two isoforms, alpha and beta, that become active upon homodimerization and cGMP binding.Arg-Lys-Arg-Ala-Arg-Lys-Glu or RKRARKE