A delta opioid receptor lacking the third cytoplasmic loop is generated byatypical mRNA processing in human malignomas

delta Opioid receptors mere identified in human melanomas by RT-PCR and rad ioligand binding. In all tumors an additional PCR amplificate was detected in which 144 bp within the third tron were deleted. This fragment correspon ded to the third cytoplasmic domain of the receptor protein, The short vari ant resulted from atypical mRNA processing, There were no common splice rec ognition sequences around the deleted fragment; instead its excision resemb led the removal of a transposon. The deletion was not detected in normal hu man melanocytes nor in human or rat brain. However, it mas present in a hum an neuroblastoma cell line (SH-SY5Y), Thus, it appears that the occurrence of the short delta opioid receptor is correlated to malignancy. (C) 2000 Fe deration of European Biochemical Societies. Published by Elsevier Science B .V. All rights reserved.