Progestin, estrogen and androgen G-protein coupled receptors in fish gonads.
The identities of the membrane receptors mediating the majority of rapid, cell surface-initiated, nongenomic (i.e. nonclassical) steroid actions described to date are unclear. Two novel 7-transmembrane spanning proteins, representing two distinct classes of steroid membrane receptors, membrane progestin receptor alpha (mPRalpha) and a membrane estrogen receptor (mER), GPR30, have recently been identified in several vertebrate species. Evidence that both receptors activate G-proteins and function as G-protein coupled receptors (GPCRs) is briefly reviewed. New data on progestin actions on fish gametes suggest a widespread involvement of mPRalpha in oocyte maturation and sperm hyperactivity in this vertebrate group. Information on the second messenger pathways activated upon estrogen binding to a membrane estrogen receptor in croaker gonads and preliminary evidence for the presence of a GPR30-like protein in fish gonads are discussed. Finally, initial characterization of the ligand binding, G-protein activation and molecular size of a membrane androgen receptor (mAR) in croaker ovaries suggests the presence of a third unique steroid receptor in fish gonads that also may function as a GPCR.
Thomas
Peter
P
University of Texas at Austin, Marine Science Institute, Port Aransas, 78374, USA. thomas@utmsi.utexas.edu
Dressing
Gwen
G
Pang
Yefei
Y
Berg
Hakan
H
Tubbs
Christopher
C
Benninghoff
Abby
A
Doughty
Kelly
K
D000818:Animals; D005260:Female; D008297:Male; D010053:Ovary / Q000378:metabolism* / Q000502:physiology; D010473:Perciformes / Q000378:metabolism* / Q000502:physiology; D011944:Receptors, Androgen / Q000502:physiology; D011960:Receptors, Estrogen / Q000502:physiology; D043562:Receptors, G-Protein-Coupled / Q000502:physiology*; D011980:Receptors, Progesterone / Q000502:physiology; D013737:Testis / Q000378:metabolism* / Q000502:physiology
D011944:Receptors, Androgen; D011960:Receptors, Estrogen; D043562:Receptors, G-Protein-Coupled; D011980:Receptors, Progesterone