The postsynaptic density (PSD) fraction prepared from rat forebrains frozen with liquid nitrogen immediately after dissection (within 30 s after decapitation) contained major postsynaptic density protein (mPSDp), a subunit of Ca2+/calmodulin-dependent protein kinase II (CaMKII) at a level of merely 2.7% of the total protein. The content ofthe protein in the fraction was increased to --10% by placing the forebrains on ice for a few minutes . Accumulation, but to a lesser extent, of the protein after placement was also observed in the particulate, synaptosome, and synaptic plasma membrane fractions with its concomitant decrease in the cytosolic fraction. The distribution change may be translocation of the protein, because the amounts of the losses of the protein in the cytosolic fraction were balanced by the gains in the particulate fractions . By translocation, CaMKII became Triton X-100 insoluble and partially inactivated . The amount of CaMKII transferred from the cytosol to particulate fractions at 0°C was about the same as that contained in the conventional PSD fraction . Furthermore, the thickness of the PSD was increased by the treatment of the forebrains at 37°C, by which the content of CaMKIla in the PSD fraction was increased to twofold . These results suggest that most of the CaMKII a subunit associated with the PSD fraction (mPSDp) is translocated from cytosol after decapitation . We also showed similar translocation of CaMKllß/ß' . Key Words: Postsynaptic density protein-Rat forebrain-Ca2+/calmodulin-dependent protein kinase II-Particulate-Cytosol .

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Familial cholesteryl ester transfer protein (CETP) deficiency is more common in some East Asian populations than elsewhere, suggesting the possibility of a selective advantage of this genetic defect against regional infectious diseases. Historically, infection with the Asian blood fluke Schistosoma japonicum has been endemic in these regions, including Japan. We previously reported that eggs of S. japonicum require cholesteryl ester uptake from normal high-density lipoprotein (HDL) but not from CETP-deficient HDL for their maturation to miracidia, a critical step of the hepatic pathogenesis of schistosomiasis. Herein we show that cholesteryl ester uptake is selective from HDL, and identified CD36-related protein (CD36RP) as a candidate to mediate the reaction. CD36RP was cloned from the adult and the egg developmental stages of S. japonicum, with 1880 bp encoding 506 amino acid residues exhibiting the CD36 domains and two transmembrane regions. Using antibodies against recombinant peptides representing the potential extracellular domains of CD36RP, Western blotting detected a protein with a molecular mass of 82 kDa in the particulate fraction of the adult parasite cells, which was reduced to 62 kDa after N-glycanase treatment. The extracellular domain peptide bound human HDL, as established by immunoblots following nondenaturing gel electrophoresis. Antibodies against the extracellular domain suppressed HDL cholesteryl ester uptake and maturation of the eggs in vitro. CD36RP is a candidate receptor on eggs of S. japonicum that facilitates uptake of HDL cholesteryl ester necessary for egg embryonation and maturation.

The distributions of IkappaB and NF-kappa B immunoreactivities were examined immunohistochemically in the rat brain by the electron microscopy. Antibodies were raised against synthetic peptides with the sequences specific to the human MAD-3 type IkappaB or NF-kappa B. Both IkappaB alpha and NF-kappa B immunoreactivities were localized in the dendrites including the spines and, particularly, the postsynaptic densities (PSDs) of the hippocampus and the cerebral cortex. The PSD fraction prepared from the rat brain contained an activity that inhibited the binding of NF-kappa B to the kappa B DNA elements. These results suggest that the NF-kappa B/IkappaB system or a similar mechanism may play a role in signal transmission from synapses to the nucleus.

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