Conformational features of a synthetic model of the first extracellular loop of the angiotensin II AT1A receptor.
The angiotensin II AT1A receptor belongs to the G-protein coupled receptors (GPCRs). Like other membrane proteins, GPCRs are not easily amenable to direct structure determination by the currently available methods. The peptide encompassing the putative first extracellular loop of AT1A (residues Thr88-Leu100, el1) has been synthesized along with a cyclic model where the linear peptide has been covalently linked to a template designed to keep the distance between the peptide termini as expected in the receptor. The conformational features of the two molecules have been studied using circular dichroism and NMR techniques. The region W94PFG97 forms a type-II beta-turn and undergoes a Trp-Pro peptide bond cis-trans isomerization in both peptides confirming that these characteristics are intrinsic to el1. In addition, the presence of the spacer seems to modulate the flexibility of the peptide.
Department of Experimental Medicine, Section of Chemistry and Structural Biochemistry, University of Parma, 43100 Parma, Italy.
Giuseppe
G
Nicastro
Francesco
F
Peri
Lorella
L
Franzoni
Cesira
C
de Chiara
Giorgio
G
Sartor
Alberto
A
Spisni
D000595:Amino Acid Sequence; D002942:Circular Dichroism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000737:chemistry; D011487:Protein Conformation; D044140:Receptor, Angiotensin, Type 1 / Q000737:chemistry*; D012997:Solvents / Q000494:pharmacology
D010446:Peptide Fragments; D044140:Receptor, Angiotensin, Type 1; D012997:Solvents