Histamine is a ubiquitous messenger molecule released from mast cells, enterochromaffin-like cells, and neurons. Its various actions are mediated by histamine receptors H1, H2, H3 and H4. Histamines are an important pharmacological mediator involved in pathophysiological processes such as allergies and inflammations. The H₁ receptor is a histamine receptor belonging to the family of Rhodopsin-like G-protein-coupled receptors. Histamine H(1) receptor  antagonists are very effective for drug targets because of their ability to alleviate the symptoms of allergic reactions. The crystal structure of the H(1)R complex with doxepin, a first-generation H(1)R antagonist.  Doxepin is a reuptake inhibitor of serotonin and norepinephrine and acts as a antagonist of various serotonin, adrenergic, muscarinic, dopamine, and histamine receptors. The Histamine complex is represented as a STL model is provided in conjunction with phospholipid membrane boundries.  The cytoplasmic and extracellular regions are determined.  The source of the model is PDB: 3RZE and the final model was generated by the server Orientations of Proteins in Membranes. Credit is due to the original authors who preformed the x-ray Crystallography  "Structure of the human histamine H1 receptor complex with doxepin." Shimamura, T., Shiroishi, M., Weyand, S., Tsujimoto, H., Winter, G., Katritch, V., Abagyan, R., Cherezov, V., Liu, W., Han, G.W., Kobayashi, T., Stevens, R.C., Iwata, S. (2011) Nature 475: 65-70.  The file is 40,302 KB in size.  It is watertight and is printable.