en Genetics Genetics پژوهشي Orginal research papers <span lang="TR" style="font-size:11.0pt"><span calibri="" style="font-family:"><span style="color:black">The g-type lysozyme is one of the three major diverse lysozyme types recognized in the animal kingdom including fish. Using the RT-PCR technique, a 555 bp cDNA fragment encoding a g-type lysozymewas isolated from the skin mucus of <i>Ctenopharyngodon idella</i> using homolog primes. The cDNA named Ci-Kh, codes for 185 amino acids with a predicted molecular weight of 20.49 kDa and theoretical pI of 9.13. The sequence consists of one cysteine residue with no predicted signal peptide. Domain analysis showed e-value of 3.74e-107 with the conserved domain of lysozyme-like superfamily (cd01021) between amino acid residues 12 to 184. Multiple alignment with the lysozyme genes from other fish species revealed </span></span></span><span lang="TR" style="font-size:11.0pt"><span calibri="" style="font-family:"><span style="color:black">that this protein have a goose egg white lysozyme (GEWL) domain containing two conserved catalytic residues (</span></span></span><span lang="TR" style="font-size:11.0pt"><span calibri="" style="font-family:"><span style="color:black">Glu73 and Asp97) </span></span></span><span lang="TR" style="font-size:11.0pt"><span calibri="" style="font-family:"><span style="color:black">and N-acetyl-D-glucosamine binding site (</span></span></span><span lang="TR" style="font-size:11.0pt"><span calibri="" style="font-family:"><span style="color:black">Glu73, Asp85, Asp97</span></span></span><span lang="TR" style="font-size:11.0pt"><span calibri="" style="font-family:"><span style="color:black">, Tyr100, His101, His102, Ile119, Tyr147, Asn148)</span></span></span><span lang="TR" style="font-size:11.0pt"><span calibri="" style="font-family:"><span style="color:black">. Protein structure prediction software revealed a prediction of 58% and 42% of <i>a</i>-helical and random coils for the coding sequence of Ci-Kh, respectively.The 3D model of Ci-Kh revealed that this protein was mainly composed of five main helices and random coils. Phylogenetic analysis indicated that Ci-Kh matched the group of five grass carp g-type lysozyme transcript variants with 86-99% similarity. Among the five variants of this gene, Ci-Kh sequence had the highest and lowest genetic distance with <i>C. idella</i> variant X2 (8.6%) and X3 (1.1%) sequences, respectively. We conclude that Ci-Kh as a different variant of g-type lysozyme cannot be ruled out.</span></span></span> G-type lysozyme, Skin mucus, Ctenopharyngodon idella 757 770 http://jifro.ir/browse.php?a_code=A-10-1538-4&slc_lang=en&sid=1 A. Jolodar jolodara@yahoo.com 100319475328460052604 100319475328460052604 Yes Shahid Chamran University of Ahvaz