[1] The domain is about 90 amino acid residues long.
The domain is known to direct RanGAP to the nuclear envelope.
[2] Non-RanGAP nuclear envelope proteins are also known to encode WPP domains, such as MFP1 attachment factor 1 (MAF1),[1] WPP1[3] and WPP2.
[3] The WPP stands for a tryptophan-proline-proline motif that is highly conserved in the domain.
[1] Either deletion of the WPP domain or mutation of both the namesake tryptophan and first proline residues into alanine in the Arabidopsis thaliana protein RanGAP1 leads to mis-targeting in the majority of cells.