Interaction of rat kidney proteins with the renalase peptide RP220 and its potential proteolytic fragment RP224-232: a comparative proteomic analysis.

Renalase (RNLS) is a protein playing different roles inside and outside cells. A 20-mer synthetic peptide corresponding to the human RNLS amino acid sequence 220-239 (RP220) exhibits a number of pharmacologically attractive activities in vitro and in vivo and can bind to many renal intracellular proteins. The RP220 sequence contains several cleavage sites for extracellular and circulating proteases. Here, we investigated the interaction of model proteins with the renalase peptide RP220 and a synthetic peptide corresponding to the amino acid sequence of RNLS 224-232, named RP224-232. We also performed affinity-based proteomic profiling of normotensive rat kidney samples with these peptides as affinity ligands. The obtained results indicate that both peptides exhibit almost the same affinity for model proteins (pyruvate kinase and lactate dehydrogenase), and the kidney proteomic profiles differ slightly. At the same time, the relative content of a number of kidney proteins bound to the RP224-232 peptide was even higher than in the case of using RP220. This suggests that proteolytic processing of RP220 does not inactivate this peptide; moreover, it could contribute to the formation of shorter peptides with additional pharmacological activities.