title: A novel calcium-binding peptide from the cuticle of the crayfish, Procambarus clarkii.
abstract: A novel peptide named calcification-associated peptide (CAP)-2 was isolated from the exoskeleton of the crayfish, Procambarus clarkii. CAP-2 consists of 65 amino acid residues and has a 44% sequence identity with CAP-1 characterized previously. It has a chitin-binding domain observed in many arthropod cuticle proteins. CAP-2 showed inhibitory activity on calcium carbonate precipitation and chitin-binding ability. A CAP-2 cDNA was cloned using RT-PCR and RACE and the open reading frame encoded a precursor peptide consisting of a signal peptide and CAP-2. RT-PCR revealed that CAP-2 mRNA was exclusively expressed in the epidermal tissue during the postmolt stage, the site and stage being associated with calcification. Calcium-binding assay using recombinant CAP-2 revealed that this peptide had affinity for calcium ions with a Kd value of about 1 mM. All these results suggest that CAP-2 serves as a nucleator or a regulator in the calcification of the exoskeleton.
authors.affiliation: Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo, Tokyo 113-8657, Japan. aa27009@mail.ecc.u-tokyo.ac.jp
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Inoue
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Ohira
authors.forename: Noriaki
authors.initials: N
authors.lastname: Ozaki
authors.forename: Hiromichi
authors.initials: H
authors.lastname: Nagasawa
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003400:Astacoidea / Q000033:anatomy & histology / Q000378:metabolism* / Q000502:physiology; D002118:Calcium / Q000378:metabolism*; D002119:Calcium Carbonate / Q000737:chemistry; D002135:Calcium-Binding Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism* / Q000494:pharmacology; D002686:Chitin / Q000378:metabolism; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D015870:Gene Expression; D008969:Molecular Sequence Data; D018978:Molting / Q000502:physiology; D010455:Peptides / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D016415:Sequence Alignment; D014018:Tissue Distribution
chemical_list: D002135:Calcium-Binding Proteins; D018076:DNA, Complementary; D010455:Peptides; D011994:Recombinant Proteins; C448763:calcification-associated peptide-1, crayfish; D002686:Chitin; D002119:Calcium Carbonate; D002118:Calcium