Molecular cloning and characterization of tiger shrimp (Penaeus monodon) transglutaminase Chih-Cheng Huang a , Kallaya Sritunyalucksana b , Kenneth So ¨derha ¨ll c , Yen-Ling Song a,d, * a Institute of Zoology, National Taiwan University, Taipei 106, Taiwan, ROC b Center of Excellence in Shrimp Molecular Biology and Biotechnology, Faculty of Science, Mahidol University, Bangkok 10250, Thailand c Department of Comparative Physiology, Evolutionary Biology Centre, Uppsala University, Sweden d Department of Life Science, National Taiwan University, Taipei 106, Taiwan, ROC Received 16 March 2003; revised 20 August 2003; accepted 27 August 2003 Abstract Transglutaminases (TG) are important for blood coagulation and post-translation remodeling of proteins. Using a plaque screening assay, we isolated cDNA encoding a novel TG from a shrimp (Penaeus monodon) hemocyte cDNA library. The TG cDNA consists of 2988 bp with an open reading frame of 2271 bp. The deduced protein has 757 amino acid residues, a calculated molecular mass of 84,713 Da and an isoelectric point of 5.56. Neither a typical hydrophobic leader sequence nor a transmembrane domain could be identified from the deduced sequence. Thus, shrimp TG may be a typical cytoplasmic protein. The sequence of shrimp TG was similar to crayfish, other invertebrate and vertebrate TG sequences. Enzyme activity was detected in all organs tested. This is consistent with the widespread, low-level expression of TG mRNA. However, high levels of TG expression were detected in hematopoietic tissue. TG signals were stronger in mitotic cells, indicating that cell proliferation and TG synthesis are associated. Preliminary data showed that recombinant TG existed the enzyme activity but lacked coagulation activity. q 2003 Elsevier Ltd. All rights reserved. Keywords: Transglutaminase; Coagulation; Penaeus monodon; Shrimp; In situ hybridization; Hematopoietic tissue; Hemocyte; Cell proliferation 1. Introduction Transglutaminases (TG) (EC 2.3.2.13) are known primarily for their roles in blood coagulation and post- translational protein remodeling. Enzymes in this family use a modified double-displacement mechan- ism to execute a calcium-dependent acyl transfer reaction between the g-carboxamide group of a peptide-bound glutamine residue and the 1-amino group of a peptide-bound lysine or the primary amino group of a polyamine. When a protein-bound lysine residue acts as an acyl acceptor, intermolecular or intramolecular 1-(g-glutamyl) lysine bonds form, resulting in protein polymerization [1–4]. 0145-305X/$ - see front matter q 2003 Elsevier Ltd. All rights reserved. doi:10.1016/j.dci.2003.08.005 Developmental and Comparative Immunology 28 (2004) 279–294 www.elsevier.com/locate/devcompimm * Corresponding author. Tel.: þ 886-223-630-231x3355; fax: þ 886-223-660-243. E-mail address: song@ccms.ntu.edu.tw (Y.-L. Song).