10.1021/bi700490n.s002
Naoyuki Sugiyama
Naoyuki
Sugiyama
Keiichi Konoki
Keiichi
Konoki
Kazuo Tachibana
Kazuo
Tachibana
Isolation and Characterization of Okadaic Acid Binding Proteins from the Marine
Sponge <i>Halichondria okadai</i><sup>†</sup>
American Chemical Society
2007
OABP 2.2 form
OABP 2.1
marine sponge Halichondria okadai
sponge Halichondria japonica
exhibit phosphatase activity
HPLC
Edman degradation
detoxifying okadaic acid
protein phosphatases 1
dinoflagellate Prorocentrum lima
OABP 1
OABP 2
biotinylated photoreactive okadaic acid
okadaic acid
okadaic acid binding protein
22 kDa proteins
rabbit PP 2A
SDS
2007-10-09 00:00:00
Journal contribution
https://acs.figshare.com/articles/journal_contribution/Isolation_and_Characterization_of_Okadaic_Acid_Binding_Proteins_from_the_Marine_Sponge_i_Halichondria_okadai_i_sup_sup_/2981986
Okadaic acid, first isolated from the marine sponge <i>Halichondria okadai</i>, is a potent inhibitor
of protein phosphatases 1 and 2A (PP1 and PP2A, respectively). Photoaffinity labeling experiments
previously performed with biotinylated photoreactive okadaic acid revealed the presence of okadaic acid
binding protein (OABP) in the crude extract of <i>H. okadai</i>. In this article, OABP1 and OABP2 were
purified from <i>H. okadai</i> as guided by the binding affinity of [27-<sup>3</sup>H]okadaic acid. OABP1 has an
approximate molecular mass of 37 kDa in SDS−PAGE analysis. Edman degradation followed by molecular
cloning and sequencing identified OABP1 as being 88% identical to the rabbit PP2Aβ catalytic subunit.
On the other hand, HPLC analysis revealed that OABP2 consists of three 22 kDa proteins (OABP2.1,
OABP2.2, and OABP2.3). Electrospray ionization mass spectrometry indicated that OABP2.1 and OABP2.2
form a complex with okadaic acid. The complete amino acid sequence of OABP2, determined by Edman
degradation and molecular cloning, showed that OABP2.1 is 96% identical to OABP2.2 and 66% identical
to OABP2.3, while being very slightly homologous to any protein phosphatases known to date. OABP2
did not exhibit phosphatase activity, though it bound to okadaic acid with a <i>K</i><sub>d</sub> of 0.97 nM. Furthermore,
OABP2 was not detected in the sponge <i>Halichondria japonica</i> or the dinoflagellate <i>Prorocentrum lima</i>.
We thus speculated that OABP2 might be involved in detoxifying okadaic acid.