Popis: |
Initial classification of dopamine (DA) receptors into D1 and D2 subtypes on the basis of stimulatory and no/inhibitory linkage to adenylyl cyclase (AC), respectively (Spano et al 1978; Kebabian and Calne 1979), endured in substance for approximately a decade until the molecular cloning of D1 and D2 receptors provided additional criteria for distinguishing these two receptors in terms of genomic structure/localization, primary structure and mRNA tissue distribution profile. Thereafter, primarily during the early 1990s, further molecular cloning studies revealed the mammalian DA receptor family to be yet more heterogeneous (see Missale et al. 1998; Neve and Neve 1997; Niznik 1994): in particular, cloning both of primate D1 (rodent homologue D1A ) and of primate D5 (rodent homologue D1B ) receptors indicated the original designation of D1 to encompass a family of D1-like receptors whose properties are t he focus of this chapter, in juxtaposition with a family of D2-like receptors (D2L/S, D3, D4) whose properties are the focus of subsequent chapters. |