Identification of an AII(3-8) [AIV] binding site in guinea pig hippocampus.
A unique angiotensin binding site specific for the hexapeptide, AII(3-8), has been identified in guinea pig hippocampus. This binding site, which is present in the pyramidal cell layer of CA1, CA2, CA3 of the hippocampus and dentate gyrus, binds AII(3-8) with high affinity (KD = 1.29 +/- 0.18 nM) in a saturable manner (Bmax = 449 +/- 62 fmol/mg protein). The N-terminal structure of the binding ligand is paramount in determining the binding affinity. The C-terminal requirements seem less stringent as evidenced by the binding affinity of AII(3-7) (KD = 20.9 +/- 2.1 nM). Neither AII, AIII,Sar1, Ile8-AII, Dup 753 nor CGP42112A appear to bind, indicating that this binding site is neither the AT1 nor AT2 sites described for AII/AIII. Autoradiographic analysis of hippocampus binding confirms the inability of Sar1,Ile8-AII to compete for [125I]AII(3-8) binding. Conversely AII(3-8) was unable to displace [125I]Sar1,Ile8-AII binding.
Harding
J W
JW
Department of Veterinary and Comparative Anatomy, Washington State University, Pullman 99164-6520.
Cook
V I
VI
Miller-Wing
A V
AV
Hanesworth
J M
JM
Sardinia
M F
MF
Hall
K L
KL
Stobb
J W
JW
Swanson
G N
GN
Coleman
J K
JK
Wright
J W
JW
D000804:Angiotensin II / Q000031:analogs & derivatives* / Q000378:metabolism; D000818:Animals; D001345:Autoradiography; D001667:Binding, Competitive; D006168:Guinea Pigs; D006624:Hippocampus / Q000378:metabolism*; D007457:Iodine Radioisotopes; D007700:Kinetics; D008297:Male; D011712:Pyramidal Tracts / Q000378:metabolism; D011945:Receptors, Angiotensin / Q000032:analysis / Q000378:metabolism*
D007457:Iodine Radioisotopes; D011945:Receptors, Angiotensin; D000804:Angiotensin II; C012877:angiotensin II, des-Asp(1)-des-Arg(2)-Ile(5)-