title: Characterization of an intracellular cystatin homolog from the tick Haemaphysalis longicornis.
abstract: Cystatins are tight-binding inhibitors of papain-like cysteine proteases. On the basis of amino acid sequencing, cystatins can be subdivided into three closely related families, family 1, family 2 and family 3. Among them, only family 1 cystatins are intracellular. In this report, a gene encoding family 1 cystatin from tick Haemaphysalis longicornis (Hlcyst-1) has been identified. Its full-length cDNA is 437 bp, including an intact ORF encoding an expected protein with 98 amino acids. Sequence analysis demonstrated that it has significant homology with the known family 1 cystatin. The recombinant protein was expressed in a GST-fused soluble form in Escherichia coli, and its inhibitory activity against papain, cathepsin L, and cathepsin B was identified by fluorogenic substrate analysis. This is the first report of an intracellular cystatin homolog from the tick H. longicornis.
authors.affiliation: Department of Frontier Veterinary Medicine, Kagoshima University, Korimoto 1-21-24, Kagoshima 890-0065, Japan.
authors.forename: Jinlin
authors.initials: J
authors.lastname: Zhou
authors.forename: Min
authors.initials: M
authors.lastname: Liao
authors.forename: Mami
authors.initials: M
authors.lastname: Ueda
authors.forename: Haiyan
authors.initials: H
authors.lastname: Gong
authors.forename: Xuenan
authors.initials: X
authors.lastname: Xuan
authors.forename: Kozo
authors.initials: K
authors.lastname: Fujisaki
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D015891:Cystatins / Q000737:chemistry* / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000502:physiology; D008969:Molecular Sequence Data; D013987:Ticks / Q000235:genetics / Q000378:metabolism*
chemical_list: D015891:Cystatins