Alternatively spliced brain-derived neurotrophic factor (BDNF) transcripts are targeted to distinct cellular compartments in neurons but the mechanisms underlying this sorting are unknown. Although only some BDNF isoforms are targeted to dendrites, we have found that the coding region common to all BDNF transcripts contains a constitutively active dendritic targeting signal and that this signal is suppressed in transcripts containing exons 1 or 4, which are restricted to the cell soma and proximal dendrites. This dendritic targeting signal is mediated by translin, an RNA-binding protein implicated in RNA trafficking, and is disrupted by the G196A mutation associated with memory deficits and psychiatric disorders. Molecular modeling and mutational studies indicate that the G196A mutation blocks dendritic targeting of BDNF mRNA by disrupting its interaction with translin. These findings implicate abnormal dendritic trafficking of BDNF mRNA in the pathophysiology of neuropsychiatric disorders linked to the G196A mutation.neuropsychiatric disorders ͉ neurotrophins S everal lines of evidence indicate that targeting of BDNF mRNA to dendrites plays a key role in mediating synaptic plasticity (1-4). However, the molecular mechanisms regulating this process and the differential subcellular localization of alternatively spliced BDNF transcripts, remain to be clarified.Multiple BDNF transcripts are generated by alternative splicing of one 5Ј exon with a shared 3Ј exon containing the entire BDNF coding region and either a short or long 3Ј UTR sequence (5, 6). In recent studies, we have demonstrated that BDNF transcripts differ in their subcellular localization (7). Exon 1 and 4 transcripts are localized in the cell soma, while exon 2 and 6 transcripts show a somato-dendritic localization. Thus, splice variants appear to encode spatial localization signals used to preferentially regulate BDNF expression in different subcellular domains (2, 3). A recent study has suggested that the long 3Ј UTR contains signals necessary for dendritic targeting of BDNF transcripts (4). However, it is unlikely that this mechanism can fully account for the differential dendritic targeting displayed by BDNF transcripts because more than one-third of exon 4 transcripts, which are retained in the soma, contain the long 3Ј UTR. Conversely, more than one-half of exon 6 transcripts, an isoform that displays targeting to dendrites, contain the short 3Ј UTR. To help define the mechanisms underlying differential localization of BDNF transcripts, we have tested the hypothesis that additional signals might be encoded by other BDNF mRNA regions.

A combined target-based and ligand-based drug design approach has been carried out to define a novel pharmacophore model of the human A(3) receptor antagonists. High throughput molecular docking and comparative molecular field analysis (CoMFA) have been used in tandem to assemble a new target based pharmacophore model. In parallel, to provide more accurate information about the putative binding site of these A(3) inhibitors, a rhodopsin-based model of the human A(3) receptor was built and a novel Y-shape binding motif has been proposed. Docking-based structure superimposition has been used to perform a quantitative study of the structure-activity relationships for binding of these pyrazolo-triazolo-pyrimidines to adenosine A(3) receptor using CoMFA. Both steric and the electrostatic contour plots obtained from the CoMFA analysis nicely fit on the hypothetical binding site obtained by molecular docking. On the basis of the combined hypothesis, we have designed, synthesized, and tested 17 new derivatives. Consistently, the predicted K(i) values were very close to the experimental values.

This study presents a computational analysis of the structures of lipase B from Candida antarctica (CalB) and two penicillin G acylases (PGAs), from eukaryotic and prokaryotic sources, respectively. Molecular simulations were used to point out the regions of the enzymes that are prone to interact with immobilisation supports. In order to evaluate the accessibility of the active site, the location of the amino acid residues involved in the formation of covalent bonds with the polymers was visualised. The mapping of the distribution of hydrophobic and hydrophilic regions on the enzyme surface provided a view of the areas of the protein that can establish either hydrophobic or hydrophilic interactions with the carriers. Experimental data obtained from the immobilisation of the enzymes on supports bearing different chemical functionalities suggest the involvement of the glycan moiety in enzyme-polymer interactions. In the case of PGA the glycan moiety can constitute an extra site for the covalent linkage of the enzyme on the polymer.