Single amino acid of g(alpha16) (Ala(228)) is responsible for the ability of chemoattractant C5a receptor to induce G(alpha16)-mediated inositol phosphate release.
Our previous study suggested that the region encompassing residues 220-240 on G(alpha16) is important in coupling with C5a receptor (Lee et al. (1995) Mol. Pharmacol. 47, 218-223). When aligned sequences are compared in the residue 220-240 segment of G(alpha16), there is a block of eight amino acids extending from residue 227 to residue 234 (227-Ile-Ala-Leu-Ile-Tyr-Leu-Ala-Ser-234) in G(alpha16) that is replaced by a heterologous block extending from amino acid residue 224 to residue 231 (224-Thr-Ser-Ile-Met-Phe-Leu-Val-Ala-231) in G(alpha11). In order to identify the specific amino acid residue necessary for coupling to C5a receptor within the extension of eight amino acids in G(alpha16), a series of chimeric G(alpha11)/G(alpha16) cDNA constructs and mutant G(alpha16) cDNAs were expressed. Then the ability of chimeras and mutant proteins to mediate C5a-induced release of inositol phosphate in transfected Cos-7 cells was tested. The results show that single amino acid Ala(228) is responsible for conferring about 40-50% of the activity of G(alpha16) induced by C5a receptor stimulation.
Ha
J H
JH
Department of Pharmacology and Institute of Biomedical Sciences, College of Medicine Hanyang University, Seoul, 133-791, Korea.
Dhanasekaran
N
N
Koh
H C
HC
Lee
C H
CH
D000409:Alanine / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D015703:Antigens, CD / Q000378:metabolism*; D001483:Base Sequence; D019556:COS Cells; D017931:DNA Primers; D019204:GTP-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D006868:Hydrolysis; D007295:Inositol Phosphates / Q000378:metabolism*; D044087:Receptor, Anaphylatoxin C5a; D011951:Receptors, Complement / Q000378:metabolism*
D015703:Antigens, CD; D017931:DNA Primers; D007295:Inositol Phosphates; D044087:Receptor, Anaphylatoxin C5a; D011951:Receptors, Complement; D019204:GTP-Binding Proteins; D000409:Alanine