the results of these experiments are shown in fig3 a and 3b the deduced amino acid sequence of clone hgri 4 seq id no 2 consists of 1434 residues relative molecular mass m r 52950 which are organized into seven putative transmembrane domains tmds that are from 56 tmd i to 96 tmd v identical to the corresponding tmds found in the human d1 receptor gene overall the receptor 39 s amino acid sequence is 49 identical to the human d1 receptor six asparagine asn residues represent potential n linked glycosylation sites and the presence of one of them near the n terminus of the protein asn 6 is a structural feature shared by all of the cloned dopamine receptors another potential n glycosylation site asn 351 is located in tmd vii and is also seen in both human and rat d1 receptors of the remaining four sites asn 74 and asn 388 are located in the putative extracellular loop between tmds iv and v the deduced hgri 4 receptor sequence also contains two cysteine residues cys 113 and cys 217 which are conserved among dopamine receptors these are located in the second and third putative extracellular loops and may be involved in the formation of a disulfide bond which could be important for stabilizing the receptor 39 s tertiary structure the deduced receptor sequence also contains several potential protein kinase phosphorylation target sites four for protein kinase a kemp amp pearson 1990 tibs 15 342 346 and three for protein kinase c graff et al 1989 j biol chem 264 11912 11919 interestingly five of.