The present invention provides an isolated nucleic acid molecule encoding an .alpha..sub.2B -adrenergic receptor, and an isolated protein which is a human .alpha..sub.2B -adrenergic receptor. The invention also provides vectors comprising DNA molecules encoding a human .alpha..sub.2B -adrenergic receptor, and vectors adapted for expression of the .alpha.2b.sub.2B -adrenergic receptor in bacterial, yeast, or mammalian cells. In addition, the invention provides a DNA probe useful for detecting nucleic acid encoding the .alpha.2b.sub.2B -adrenergic receptor, a method for determining whether a ligand which is not known to be capable of binding to the .alpha.2b.sub.2B -adrenergic receptor can bind to the .alpha..sub.2B -adrenergic receptor on the surface of a cell, and a method of screening drugs to identify drugs to identify drugs which specifically interact with, and bind to, the .alpha..sub.2B -adrenergic receptor. The invention herein also concern an antibody directed to the human .alpha..sub.2B -adrenergic receptor, such as a monoclonal antibody directed to an epitope of the .alpha..sub.2B -adrenergic receptor present on the surface of a cell and having an amino acid sequence included within the amino acid sequence shown in FIG. 2.