Myosin is considered as the vital motor protein in vertebrates and invertebrates. Our present study was conducted to decipher the occurrence of myosin in dog fish (Squalus mitsukurii). We isolated one clone containing 979 bp cDNA sequence, which consisted of a complete coding sequence of 453 bp and a deduced amino acid sequence of 150 amino acids from the open reading frame with molecular weight, isoelectric point and aliphatic index are 16.72 Kda, 4.49 and 78.00, respectively. It contained 428 bp long 3' UTR with single potential polyadenylation signals (AATAAA). The predicted EF CA2+ binding domains were identified in residue 6-41, 83-118 and 133-150. A BLAST search indicates this protein exhibits a strong similarity to whale shark (Rhincodon typus) MLC3 (91% identical) and also house mouse (Mus musculus) MLC isoform 3f (81% identical). Phylogenetic analysis revealed that this protein is a MLC 3 isoform like protein. This protein also demonstrates highly conserved region with other myosin proteins. Homology modeling of S. mitsukuri was performed using crystal structure of Gallus gallus skeletal muscle myosin II based on high similarity. Reverse transcription-polymerase chain reaction (PCR), quantitative PCR results exhibits dogfish myosin protein is highly expressed in muscle tissue.

Introduction
Materials and Methods
    1. Sample collection
    2. RNA extraction
    3. Molecular cloning of myosin light chain
    4. Sequence analysis
    5. Phylogenetic analysis
    6. Template identification and homology modelingof myosin protein in S. mitsukuri
    7. Semi-quantitative RT-PCR expression analysis
    8. Quantitative PCR expression analysis
Results and Discussion
    1. Isolation and Identification of the MLC cDNAclones
    2. Phylogenetic tree
    3. 3D modeling
    4. Tissue specific mRNA expression

• Soo Cheol Kim(Department of Biomedical and Electronic Engineering, Chonnam National University, Yeosu 59262, Korea)
• Kanij Rukshana Sumi(Department of Fisheries Science, College of Fisheries and Ocean Sciences, Chonnam National University, Yeosu 59626, Korea)
• Md Rajib Sharker(Department of Fisheries Science, College of Fisheries and Ocean Sciences, Chonnam National University, Yeosu 59626, Korea)
• Kang Hee Kho(Department of Fisheries Science, College of Fisheries and Ocean Sciences, Chonnam National University, Yeosu 59626, Korea) Corresponding author