Phylogenetic Analysis of Relaxin-3 Protein Amino Acid Sequence across Vertebrate Species

Abstract

Background: Relaxin-3 (RLN3) is a highly conserved protein hormone found in species such as flies, fish, rodents, and humans. Initially discovered as a neuropeptide, it modulates arousal, stress response, feeding, metabolism, and memory. It also mediates peripheral actions during pregnancy and has been found to relax the pelvic ligaments in guinea pigs. Due to its crucial role in human neuronal process modulation, dysregulation of Relaxin-3 is often associated with mental illnesses, leading to the emergence of Relaxin-3-based drugs as potential therapeutic agents. Objectives: To re-examine the evolutionary relationship between vertebrates of different genera to decipher a conserved domain evolutionary relationship with the reference species Homo sapiens, using several bioinformatics tools Methods: This study commenced with a comprehensive literature review, followed by selecting 28 vertebrate species known to possess the Relaxin-3 protein. The amino acid sequences were retrieved using FASTA and subsequently analysed through BLAST for sequence comparison. Multiple sequence alignment was conducted using Clustal Omega, followed by constructing a phylogenetic tree and a conserved domain search to elucidate evolutionary relationships and functional characteristics. Results: Phylogenetic tree suggested the close relation of Homo sapiens and Piliocolobus tephrosceles (primate), Conserved domain sequences confirmed the evolutionary relationship of Relaxin-3 protein in Piliocolobus tephrosceles to Homo sapiens with 92.957% similarity followed by Pogona vitticeps (reptile) with 22.535%. Zonotrichia albicolis (Aves) shows more similarity to Homo sapiens, than Rhincodon typus (Orectolobiformes) and Maylandia zebra (Pisces: perciformes) with 20.512% in conserved domain sequence analysis. These findings indicate that Relaxin-3 protein is highly conserved across species, and the protein's evolutionary divergence reflects the varying degrees of neural complexity among vertebrates. Conclusions: Cladistics confirmed Relaxin-3’s monophyletic conservation in primates (92.96% similarity), with divergent but functional retention in reptiles (22.54%) and birds (20.51%). Phylogeny mirrors vertebrate neural complexity, though deeper divergences require further resolution.