Figure 3
Limited proteolysis and dynamic behaviour of the linker. (a) Sequence of the linker of PTPN4 with the potential sites of cleavage of chymotrypsin and trypsin indicated by C and T, respectively. (b) Gel SDS-PAGE after one-hour incubation at 37 °C of PDZ-PTPWT with proteases at a ratio (w:w) of 1:1000 for papain:PDZ-PTPWT and subtilisin:PDZ-PTPWT, and 1:100 for trypsin:PDZ-PTPWT and chymotrypsin:PDZ-PTPWT. Black lines indicate the grouping of the same gel. The most intense bands whose N-terminal sequences were identified by mass spectrometry are numbered. Identification of N-terminal sequences of the proteolytic fragments and cleavage localizations on PTPN4 are reported in the table. (c) Transverse 15N relaxation rates (R2) of the linker within several constructs of PTPN4: unliganded PDZ-linker (green), unliganded PDZ-PTPC/S (black), PBM-liganded PDZ-linker (blue) and PBM-liganded PDZ-PTPC/S (red). The PBM peptide used is Cyto8-RETEV.
