Use of high affinity, radioiodinated probes for identification of imidazoline/guanidinium receptive sites.
Various pharmacologically active compounds with an imidazoline or guanidinium moiety are recognized by membrane bound proteins that appear structurally and functionally distinct from known hormone receptors. Such entities are termed imidazoline binding sites, I receptors, or imidazoline/guanidinium receptive sites (IGRS). To facilitate the identification and structural analysis of IGRS, we developed functionalized molecular probes exhibiting high affinity and selectivity for IGRS. The molecular probes are structurally related to cirazoline, and imidazoline that exhibits high affinity for IGRS in both central and peripheral tissues. The parent molecule 2-[3-aminophenoxy]methyl imidazoline (125I-AMIPI), which was used to identify IGRS in brain and peripheral tissues. 125I-AMIPI was converted to the photosensitive arylazide derivative (125I-AMIPI) and used to identify the M(r) of the ligand binding subunit of IGRS in various tissues including brain, pancreas, kidney, and liver. The results of these studies indicate that there are multiple binding proteins for these molecules that differ in their apparent molecular weight, tissue distribution, intratissue location, and ligand recognition properties.
Lanier
S M
SM
Department of Pharmacology, Medical University of South Carolina, Charleston 29425, USA.
Lanier
B
B
Bakthavachalam
V
V
McGrath
C R
CR
Neumeyer
J L
JL
D000818:Animals; D019791:Guanidine; D006146:Guanidines / Q000378:metabolism*; D007093:Imidazoles / Q000378:metabolism*; D054755:Imidazoline Receptors; D007457:Iodine Radioisotopes; D015335:Molecular Probes; D011869:Radioligand Assay; D011955:Receptors, Drug / Q000378:metabolism*
D006146:Guanidines; D007093:Imidazoles; D054755:Imidazoline Receptors; D007457:Iodine Radioisotopes; D015335:Molecular Probes; D011955:Receptors, Drug; D019791:Guanidine