Molecular modeling of the rabbit colonic (HKalpha2a) H+, K+ ATPase.
A model of the HKalpha2a subunit of the rabbit colonic H+, K+ ATPase has been generated using the crystal structure of the Ca(+2) ATPase as a template. A pairwise sequence alignment of the deduced primary sequences of the two proteins demonstrated that they share 29% amino acid sequence identity and 47% similarity. Using O (version 7) the model of HKalpha2a was constructed by interactively mutating, deleting, and inserting the amino acids that differed between the pairwise sequence alignment of the Ca(+2) ATPase and HKalpha2a. Insertions and deletions in the HKalpha2a sequence occur in apparent extra-membraneous loop regions. The HKalpha2a model was energy minimized and globally refined to a level comparable to that of the Ca(+2) ATPase structure using CNS. The charge distribution over the surface of HKalpha2a was evaluated in GRASP and possible secondary structure elements of HKalpha2a were visualized in BOBSCRIPT. Conservation and placement of residues that may be involved in ouabain binding by the H+, K+ ATPase were considered and a putative location for the beta subunit was postulated within the structure.
Gumz
Michelle L
ML
Department of Biochemistry and Molecular Biology, University of Florida, 1600 SW Archer Rd., Box 100245 JHMHSC, Gainesville, FL 32610, USA.
Duda
David
D
McKenna
Robert
R
Wingo
Charles S
CS
Cain
Brian D
BD
D000595:Amino Acid Sequence; D000818:Animals; D017124:Conserved Sequence; D017506:H(+)-K(+)-Exchanging ATPase / Q000737:chemistry*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D021122:Protein Subunits / Q000737:chemistry; D011817:Rabbits; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D040681:Structural Homology, Protein
D021122:Protein Subunits; D017506:H(+)-K(+)-Exchanging ATPase