Research Article Comparative Genomic Characterization of Relaxin Peptide Family in Cattle and Buffalo Muhammad Saif-ur Rehman, 1 Faiz-ul Hassan , 1 Zia-ur Rehman, 2 Hafiz Noubahar Hussain, 3 Muhammad Adnan Shahid, 1 Muhammad Mushahid , 1 and Borhan Shokrollahi 4 1 Institute of Animal and Dairy Sciences, University of Agriculture, Faisalabad 38040, Pakistan 2 University of Agriculture Faisalabad-Sub Campus, Toba Tek Singh 36050, Pakistan 3 Animal Science Division, Nuclear Institute for Agriculture and Biology (NIAB), Faisalabad, Pakistan 4 Department of Animal Science, Sanandaj Branch, Islamic Azad University, Sanandaj, Iran Correspondence should be addressed to Borhan Shokrollahi; borhansh@iausdj.ac.ir Received 30 July 2022; Accepted 9 September 2022; Published  October 2022 Academic Editor: Akhtar Ali Copyright © 2022 Muhammad Saif-ur Rehman et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Relaxin family peptides significantly regulate reproduction, nutrient metabolism, and immune response in mammals. The present study aimed to identify and characterize the relaxin family peptides in cattle and buffalo at the genome level. The genomic and proteomic sequences of cattle, buffalo, goat, sheep, horse, and camel were accessed through the NCBI database, and BLAST was performed. We identified four relaxin peptides genes (RLN3, INSL3, INSL5, and INSL6) in Bos taurus, whereas three relaxin genes (RLN3, INSL3, and INSL6) in Bubalus bubalis. Evolutionary analysis revealed the conserved nature of relaxin family peptides in buffalo and cattle. Physicochemical properties revealed that relaxin proteins were thermostable, hydrophilic, and basic peptides except for INSL5 which was an acidic peptide. Three nonsynonymous mutations (two in RLN3 at positions A16 > T and P29 > A, and one in INSL6 at position R32 > Q) in Bos taurus, whereas two nonsynonymous mutations (one in RLN3 at positions G105 > w and one in INSL3 at position G22 > R) in Bubalus bubalis, were identified. INSL3 had one indel (insertion) at position 55 in Bos taurus. Gene duplication analysis revealed predominantly segmental duplications (INSL5/ RLN3 and INSL6/INSL3 gene pairs) that helped expand this gene family, whereas Bubalus bubalis showed primarily tandem duplication (INSL3/RLN3). Our study concluded that relaxin family peptides remained conserved during the evolution, and gene duplications might help to adapt and enrich specific functions like reproduction, nutrient metabolism, and immune response. Further, the nonsynonymous mutations identified potentially affect these functions in buffalo. 1. Introduction The relaxin peptide family comprises seven peptides with significant structural similarities but low sequence resem- blance. It includes seven genes, relaxin like RLN1, -2, and -3, and insulin-like INSL3, -4, -5, and -6 in most mammals [1], but their number varies. These peptides show a high sequence resemblance with insulin due to the presence of six cysteine residues that provide the 2 interchain and 1 intrachain disulphide linkages. Each relaxin peptide family member is constituted of two chains called A and B chains [2]. These chains are connected by two disulfide bonds pres- ent between them and one disulfide bond within the A chain. Each chain contained the cysteine residues together with distinctive disulfide bonding, which are found con- served across all family members [2]. The RLN1 and RLN2 are present in humans and higher primates like apes. Both are referred to as relaxin as human RLN2 is an orthologue to RLN1 in other mammals [1, 3]. RLN3 was first identified in 2002 and is considered the com- mon ancestral gene for all relaxin peptides [2, 4]. RLN1 and its orthologue RLN2 play an important role in reproduction Hindawi BioMed Research International Volume 2022, Article ID 1581714, 11 pages https://doi.org/10.1155/2022/1581714