Chromosomal gene location | 3q25 | 5q35.2 | 20q13.33 | 18q11.2 |
Amino acids | 487 | 359 | 445 | 390 |
Isoforms | | | at least 20 (65, 66) | >3 |
G protein coupling | Gαq/11 | Gαs | Gαi/o | Gαi/o |
Constitutive activity | + | + | ++ | ++ |
Signal transduction | PLC↑, Ca2+↑ | cAMP↑ | cAMP↓, Ca2+↑, MAPK↑ | cAMP↓, Ca2+↑, MAPK↑ |
Tissue localizations | Ubiquitous (mainly lung, CNS, blood vessels) | Ubiquitous (mainly stomach, heart, CNS) | Neurons (CNS and PNS) | Bone marrow, hematopoietic cells |
Physiologic relevance | Bronchoconstriction, vasodilation, food intake, sleep-wake regulation | Gastric acid secretion | Neurotransmitter release (→ sleep-wake regulation, attention/cognition, food intake) | Immune responses (→ chemotaxis, IL-, IFN-modulation) |
Pathophysiological conditions | Allergic reactions, emesis, sleep-wake disorders | Gastric ulcers | Cognitive impairment, schizophrenia, sleep-wake disorders, epilepsy, pain, etc. | Inflammatory diseases (allergy, asthma, pruritus, arthritis), pain, etc. |