Figure 2. Phosphoinositide consensus sequence and substrate specificity.

A, amino acid alignment of the active centres of PTENs and VSPs. Human has two orthologue genes of VSP, TPTE and TPIP. Both genes give rise to several alternatively spliced variants (Walker et al. 2001). Mouse genome has one VSP-like gene, mTPTE, that gives rise to at least three alternatively spliced variants including TPTE-A. There is one amino acid difference between VSP and PTEN (glycine for VSP and alanine, for PTEN). B, comparison of enzyme activities of Ci-VSP and human PTEN using a malachite green assay (from Iwasaki et al. 2008). Activities toward a panel of synthetic di-C₁₆-phosphoinositides were determined. The relative activities of Ci-VSP and PTEN for the panel of phospholipids were calculated from their specific activities divided by the specific activities against PI(3,4,5)P₃.