Delta receptors heterogeneity

At least three hypotheses were proposed to explain pharmacological data suggesting delta receptor heterogeneity. The more conservative hypothesis was the existence of at least two distinct delta receptor proteins, encoded by two distinct mRNA species. A more imaginative hypothesis, proposed by... 

Xu H, Partilla JS, de Costa BR, Rice KC, Rothman RB. Differential binding of opioid peptides and other drugs to two subtypes of opioid deltancx binding sites in mouse brain further evidence for delta receptor heterogeneity. Peptides 1993 14 893-907. 

Fang, L., Knapp, R.J., Horvath, R., Matsunaga, T. O., Haaseth, R. C., Hruby, V. J., Porreca, F., Yamamura, H. I. Characterization of fl-IJnaltrindole binding to delta opioid receptors in mouse brain and mouse vas deferens Evidence for delta opioid receptor heterogeneity, J. Pharmacol. Exp. Ther. 1994, 268, 836-846. 

Opioid receptors comprise a heterogenous group that can be divided into at least four biochemically and topographically distinct sub-types, designated mu, kappa, sigma, and delta. Martin et al. ... 

Pharmacological subtypes of delta opioid receptors have been described. However, primary sequence analysis of transcripts has failed to provide an explanation for this pharmacological heterogeneity. This issue has been ad-... 

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