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A recent report indicates that GPR55 may be a new cannabinoid receptor sensitive to CP55940, a rather classical cannabinoid-like structure, and not to the alkylindole WIN55212-2 as previously thought (1). This analysis was made on the basis of sequence similarity between a number of GPR55 subdomains and the corresponding sequences of 'classic' cannabinoid receptors, CB 1 and CB 2 , and reinforced by the patent issued by AstraZeneca (2) showing that GPR55 is, indeed, pharmacologically a cannabinoid receptor. While the existence of additional cannabinoid receptors was suggested by several non-classical pharmacological responses (3-6), this was never clearly demonstrated.Mining our GPCR knowledge database (7), which includes biological activities related to mutagenesis experiments that have been collected and structured, we were able to determine an ensemble of amino acids residues, referred as 'functional fingerprint', involved in the binding and/or activity of a set of ligands potentially common to CB 1 , CB 2 and GPR55. Ligands considered in this study were D 9 -tetrahydrocannabinol, CP55934, HU210, JWH051 and JWH057. Each of these compounds can be considered members of the classical cannabinoid family derived from natural terpenes. Rimonabant (SR141716), which is structurally quite dissimilar, was not considered albeit if the existence of hCB 1 -related mutagenesis experiments reported in the literature. Additional residues studied in molecular modelling with cannabinoid-like structures were considered. In the case of hCB 2 , and acknowledging the paucity of the literature on mutagenesis for this sequence, some residues modulating the binding of SR144528 or JWH015 were included.AurTAG is a semi-automatic annotation tool developed at Aureus (7), and it serves to retrieve all the amino acids for a given sequence involved in the regulation of binding or activity. By using AurTAG, we were able to define a functional fingerprint for both CB 1 and hCB 2 receptors (Table 1 and Figure 1). These annotations are based on the ratio between the values of key parameters of specific ligands. In the present study K i , IC 50 or EC 50 from binding and second messenger-based activity tests were considered for a series of semi-synthetic cannabinoids. The hGPR55 sequence (Uniprot Q9Y2T6) was then aligned with hCB 1 and hCB 2 receptors (Uniprot P21554 and P34972, respectively) using ClustalW and the Blosum matrix in order to retrieve the hGPR55 amino acids aligned with those identified as key for the interaction of semi-synthetic cannabinoids with their 'classical' receptors.The hCB 2 receptor (Figure 1) only shares 44% homology with hCB 1 receptor, however it exhibits a high homology to hCB 1 functional fingerprint and hCB 1 exhibits a high homology to hCB 2 functional fingerprint. These relationships are in accordance with the fact that the two receptors probably share common features in their binding pocket for synthetic cannabinoids. In contrast, hGPR55 does not appear to share similar fingerprint with any of the classical CB ...

A dynamic heterogeneity which correlates with the function of the operator DNA in the lactose operon of E. coli. was previously observed (1) as a local minimum in the thymine imino proton T1 centered at a GTG/C-CAC sequence. Since this triplet occurs frequently in DNA regulatory regions, it was proposed that these sequences may be part of a structural element for specific protein interaction. We examine here three additional biologically significant 17 base pair duplexes containing GTG/CAC triplets: (1) a sequence from the mouse heavy chain immunoglobulin enhancer, (2) a sequence from the critical core of the Simian Virus 40 (SV40) enhancer, and (3) a sequence from pBR322 plasmid used as control for experiments with the SV40 DNA sequences. The 1H NMR resonance assignment for nearly all the nonexchangeable protons for both eukaryotic enhancer duplexes with the exception of the H5'/H5" protons was accomplished to use for structural analysis of these duplexes. The data presented show several NOE's associated with the GTG/CAC triplets which suggest structural variation from uniform B-DNA. In addition, anomalous broad crosspeaks for the fixed thymine methyl to its own H6 proton in combination with the imino proton kinetics associated with these triplets reinforces the original observation of a sequence dependent dynamic variation.

The objective of this study was to determine whether the rates of deamidation of Asn8 in selected growth hormone releasing factor (GRF) analogs were related to the peptide's secondary structures in solution. Bovine or human [Leu27]GRF(1–32)NH2 (both having Gly at position 15), [Ala15 Leu27]bGRF(1–32)NH2 and [Pro15 Leu27]bGRF(1–32)NH2 were used as model peptides. The peptide helical content (assessed by CD) increased with the increasing methanol concentration and was as follows: 7, 12 and 18% in 0% MeOH; 24, 48 and 52% in 40% MeOH; and 41, 77 and 81% in 80% MeOH for Pro15 Leu27 bGRF(1–32)NH2, [Leu27]hGRF(1–32)NH2, and Ala15 Leu27 bGRF(1–32)NH2, respectively. 2D NMR studies done in the presence of 40% CD3OH indicated more helical structure for the Ala15 analog as compared to [Len27]hGRF(1–32)NH2. In both these peptides Asn8 was included in the helical region. In contrast, the lack of conformational information for the Pro15 analog indicated little helical structure around Asn8. The peptides’ deamidation rates decreased and their half‐lives increased with increasing MeOH concentrations. At 40% MeOH, the least helical Pro15 bGRF analog (t1/2= 10.78 h) deamidated 1.5 and 2 times faster than its Gly15 (t1/2= 15.74 h) and Ala15 (t1/2= 21.53 h) counterparts, respectively. This study indicates that helical environment around Asn8 in GRF makes this residue less prone to deamidation.

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