Evolutionary analysis of the lysine-rich N-terminal cytoplasmic domains of the gastric H+,K+-ATPase and the Na+,K+-ATPase
| Autor: | Dil Diaz, Ronald J. Clarke |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2018 |
| Předmět: |
0301 basic medicine
Physiology Lysine Biophysics amino acid sequence analysis complex mixtures Serine 03 medical and health sciences sodium pump Na+/K+-ATPase Protein kinase A Protein kinase C 030102 biochemistry & molecular biology Chemistry Cell Biology Proton pump 030104 developmental biology Ion pump Cytoplasm stomach pH gastric proton pump bacteria protein intrinsic disorder 030403 - Characterisation of Biological Macromolecules [FoR] protein kinase C |
| Popis: | The catalytic α-subunits of both the Na+,K+-ATPase and the gastric H+,K+-ATPase possess lysine-rich N-termini which project into the cytoplasm. Due to conflicting experimental results it is currently unclear whether the N-termini play a role in ion pump function or regulation, and, if they do, by what mechanism. Comparison of the lysine frequencies of the N-termini of both proteins with those of all of their extramembrane domains showed that the N-terminal lysine frequencies are far higher than one would expect simply from exposure to the aqueous solvent. The lysine frequency was found to vary significantly between different vertebrate classes, but this is due predominantly to a change in N-terminal length. As evidenced by a comparison between fish and mammals, an evolutionary trend towards an increase of the length of the N-terminus of the H+,K+-ATPase on going from an ancestral fish to mammals could be identified. This evolutionary trend supports the hypothesis that the N-terminus is important in ion pump function or regulation. In placental mammals, one of the lysines is replaced by serine (Ser-27), which is a target for protein kinase C. In most other animal species a lysine occupies this position and hence no protein kinase C target is present. Interaction with protein kinase C is thus not the primary role of the lysine-rich N-terminus. The disordered structure of the N-terminus may, via increased flexibility, facilitate interaction with another binding partner, e.g. the surrounding membrane, or help to stabilize particular enzyme conformations via the increased entropy it produces. Australian Research Council |
| Databáze: | OpenAIRE |
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