title: Transmembrane domain interactions affect the stability of the extracellular domain of the human NTPDase 2.
abstract: Human NTPDase2 and chicken NTPDase8 are cell surface nucleotidases that contain two transmembrane domains (TMD) and five apyrase conserved regions (ACRs). ACR1 is located near the N-terminal TMD whereas ACR5 is located near the C-terminal TMD. The human NTPDase2 activity is decreased by low concentration of NP-40 and at temperatures higher than 37 degrees C, and undergoes substrate inactivation, whereas the chicken NTPDase8 activity is not. When freed from membrane anchorage, the soluble human NTPDase2 is no longer inactivated by detergents, high temperature, and substrate. These characteristics are retained in the hu-ck ACR1,5 chimera in which the extracellular domain is anchored to the membrane by the two TMDs of the chicken NTPDase8. The hu-ck ACR1,5 chimera is the first chimeric NTPDase reported that shows a resistance to membrane perturbation and substrate inactivation. Our results indicate that the strengths of interaction of the respective TMD pairs of the human NTPDase2 and chicken NTPDase8 determine their different responses to membrane perturbation and substrate.
authors.affiliation: Department of Chemistry and Biochemistry, San Diego State University, 5500 Campanile Drive, San Diego, CA 92182-1030, USA.
authors.forename: Wei-Chieh
authors.initials: WC
authors.lastname: Chiang
authors.forename: Aileen F
authors.initials: AF
authors.lastname: Knowles
mesh_terms: D000244:Adenosine Diphosphate / Q000737:chemistry; D000251:Adenosine Triphosphatases / Q000737:chemistry*; D000255:Adenosine Triphosphate / Q000737:chemistry; D000818:Animals; D001081:Apyrase / Q000737:chemistry*; D002462:Cell Membrane / Q000737:chemistry*; D002645:Chickens; D004789:Enzyme Activation; D006801:Humans; D017830:Octoxynol; D011092:Polyethylene Glycols / Q000737:chemistry; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000737:chemistry; D013379:Substrate Specificity; D013696:Temperature
chemical_list: D011993:Recombinant Fusion Proteins; D011092:Polyethylene Glycols; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D017830:Octoxynol; C010615:Nonidet P-40; D000251:Adenosine Triphosphatases; C027201:ectoATPase; D001081:Apyrase