The pacifastin inhibitor family web site
[Introduction] [Sequences] [Alignments] [Structures] [Phylogenetics] [References]
Created and maintained by Zoltán Gáspári
E-mail: szpari@para.chem.elte.hu
Last modified: 21.05.2003
Introduction
This site is an effort to gather all avaliable information on the family. If you wish to add new data, please write to szpari@para.chem.elte.hu.
See also the I19 inhibitor family in the MEROPS database.
The pacifastin inhibitor family is a newly established family of small serine protease inhibitors. Members are ~35-residues long and can be characterized by a simple fold consisting of three antiparalel β-strands stabilized by three disulfide bridges.
The most well-characterized members of the family are inhibitors from the migratory locust Locusta migratoria and the desert locust Schistocerca gregaria. The inhibitors are found in many tissues, e.g. the brain, fat body, ovaries of the insects. Their physiological role is not yet fully understood, the expression pattern of the molecules varies with tissue, developmental stage (Simonet et al. (2002): Cloning of two cDNAs encoding isoforms of a pacifastin-related precursor polypeptide in the desert locust, Scistocerca gregaria: analysis of stage- and tissue-dependent expression. Insect Mol. Biol. 11, 353-360), and, as demonstrated recently in desert locust, in solitary-gregarious transition (Rahman et al. (2002): Search for peptidic molecular markers in hemolyph os crowd-(gregarious) and isolated-reared (solitary) desert locusts, Schistocerca gregaria. Peptides 23, 1907-1914).
The name of the family comes from the protein pacifastin: its light chain domain contains nine inhibitory modules of the family (Liang et al. (1997): Pacifastin, a novel 155-kDa heterodimeric proteinase inhibitor containing a unique transferrin chain. Proc. Natl. Acad. sci. U.S.A. 94, 6682-6687). The name 'grasshopper family' was used by Laskowski in a recent review of protease inhibitors (Laskowski & Qasim (2000):What can the structures of enzyme-inhibitor complexes tell us about the structures of enzyme substrate complexes? Biochim. Biophys. Acta 1477, 324-337).
The most recent review of the family is: Simonet et al. (2002) Structural and functional properties of a novel serine protease inhibiting peptide family in arthropods. Comp. Biochem. Biophys. B 132, 247-255.