In plants there are various kinds of P-type ATPases. What is difference between P4-ATPase and P5-ATPase?
There are numerous differences between the various subtypes of P-type ATPases, simply because they have different amino acid sequences. Three important differences between P4 and P5 subtypes of P-type ATPases are the following:
- Structurally, P4 ATPases have their supporting structural domain (S) in the C-terminus, while P5 ATPases have the S domain divided over the N and C termini. Figure 1 shows the basic structure of P-type ATPases.
- Structurally, P4-ATPAses require a beta-subunit for proper function (Poulsen et al., 2008). As the substrate for P5-ATPases is unknown, it could not yet be tested if they also require a beta-subunit.
- Functionally, P4-ATPases are putative lipid flippases, while P5-ATPase pumps have so far (per the 2011 report cited) no assigned substrate specificity.
Schematic outline of P-type ATPases. Source: Palmgren & Poul Nissen (2011)