Conformational flexibility of three cytoplasmic segments of the angiotensin II AT1A receptor: a circular dichroism and fluorescence spectroscopy study.
The conformation of three synthetic peptides encompassing the proximal and distal half of the third intracellular loop (Ni3 and Ci3) and a portion of the cytoplasmic tail (fCT) of the angiotensin II AT1A receptor has been studied using circular dischroism and fluorescence spectroscopies. The results show that the conformation of the peptides is modulated in various ways by the environmental conditions (pH, ionic strength and dielectric constant). Indeed, Ni3 and fCT fold into helical structures that possess distinct stability and polarity due to the diverse forces involved: mainly polar interactions in the first case and a combination of polar and hydrophobic interactions in the second. The presence of these various features also produce distinct intermolecular interactions. Ci3, instead, exists as an ensemble of partially folded states in equilibrium. Since the corresponding regions of the angiotensin II AT1A receptor are known to play an important role in the receptor function, due to their ability to undergo conformational changes, these data provide some new clues about their different conformational plasticity.
Pertinhez
Thelma A
TA
Center for Molecular and Structural Biology, LNLS, CP, Campinas, Brazil.
Krybus
Regina
R
Cilli
Eduardo M
EM
Paivac
Antonio C M
AC
Nakaie
Clóvis R
CR
Franzoni
Lorella
L
Sartor
Giorgio
G
Spisni
Alberto
A
Schreier
Shirley
S
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000737:chemistry; D000804:Angiotensin II / Q000737:chemistry*; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D002942:Circular Dichroism; D003593:Cytoplasm / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D010452:Peptide Biosynthesis; D010455:Peptides / Q000737:chemistry; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D051381:Rats; D044140:Receptor, Angiotensin, Type 1; D011945:Receptors, Angiotensin / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D013696:Temperature
D000596:Amino Acids; D010455:Peptides; D044140:Receptor, Angiotensin, Type 1; D011945:Receptors, Angiotensin; D000804:Angiotensin II