title: Identification of okadaic acid binding protein 2 in reconstituted sponge cell clusters from Halichondria okadai and its contribution to the detoxification of okadaic acid.
abstract: Okadaic acid (OA) and OA binding protein 2 (OABP2) were previously isolated from the marine sponge Halichondria okadai. Because the amino acid sequence of OABP2 is completely different from that of protein phosphatase 2A, a well-known target of OA, we have been investigating the production and function of OABP2. In the present study, we hypothesized that OABP2 plays a role in the detoxification of OA in H. okadai and that the OA concentrations are in proportional to the OABP2 concentrations in the sponge specimens. Based on the OA concentrations and the OABP2 concentrations in the sponge specimens collected in various places and in different seasons, however, we could not determine a positive correlation between OA and OABP2. We then attempted to determine distribution of OA and OABP2 in the sponge specimen. When the mixture of dissociated sponge cells and symbiotic species were separated with various pore-sized nylon meshes, most of the OA and OABP2 was detected from the same 0-10 μm fraction. Next, when sponge cell clusters were prepared from a mixture of dissociated sponge cells and symbiotic species in the presence of penicillin and streptomycin, we identified the 18S rDNA of H. okadai and the gene of OABP2 in the analysis of genomic DNA but could not detect OA by LC-MS/MS. We thus concluded that the sponge cells express OABP2, and that OA was not apparently present in the sponge cells but could be colocalized with OABP2 in the sponge cells at a concentration less than the limit of detection.
authors.affiliation: Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori-Amamiyamachi, Aoba-ku, Sendai, Miyagi 981-8555, Japan. Electronic address: konoki@m.tohoku.ac.jp.
authors.forename: Keiichi
authors.initials: K
authors.lastname: Konoki
authors.affiliation: Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori-Amamiyamachi, Aoba-ku, Sendai, Miyagi 981-8555, Japan.
authors.forename: Kayo
authors.initials: K
authors.lastname: Okada
authors.affiliation: Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori-Amamiyamachi, Aoba-ku, Sendai, Miyagi 981-8555, Japan.
authors.forename: Mami
authors.initials: M
authors.lastname: Kohama
authors.affiliation: Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori-Amamiyamachi, Aoba-ku, Sendai, Miyagi 981-8555, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Matsuura
authors.affiliation: Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori-Amamiyamachi, Aoba-ku, Sendai, Miyagi 981-8555, Japan.
authors.forename: Kaori
authors.initials: K
authors.lastname: Saito
authors.affiliation: Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori-Amamiyamachi, Aoba-ku, Sendai, Miyagi 981-8555, Japan.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Cho
authors.affiliation: Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori-Amamiyamachi, Aoba-ku, Sendai, Miyagi 981-8555, Japan.
authors.forename: Goh
authors.initials: G
authors.lastname: Nishitani
authors.affiliation: Graduate School of Pharmaceutical Sciences, Kyushu University, Maidashi 3-1-1, Higashi-ku, Fukuoka 812-8582, Japan.
authors.forename: Tomofumi
authors.initials: T
authors.lastname: Miyamoto
authors.affiliation: Graduate School of Science, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Seketsu
authors.initials: S
authors.lastname: Fukuzawa
authors.affiliation: Graduate School of Science, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Tachibana
authors.affiliation: Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori-Amamiyamachi, Aoba-ku, Sendai, Miyagi 981-8555, Japan.
authors.forename: Mari
authors.initials: M
authors.lastname: Yotsu-Yamashita
mesh_terms: D000818:Animals; D008658:Inactivation, Metabolic; D019319:Okadaic Acid / Q000737:chemistry / Q000378:metabolism; D011161:Porifera / Q000235:genetics / Q000378:metabolism*; D011506:Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D011506:Proteins; D019319:Okadaic Acid
keywords: Detoxification; Halichondria okadai; Okadaic acid; Okadaic acid binding protein