Analysis of the REJ Module of Polycystin-1 Using Molecular Modeling and Force-Spectroscopy Techniques
Figure 2
Analysis of the mechanical stability of putative REJ domains 1 and 2. (a) Typical unfolding pattern of the MBP-REJd1,2-I27 protein. The first two peaks in the force-extension curve correspond to the unfolding of MBP, with a total increase in ΔLc of about 100 nm (red double headed arrow) and an unfolding intermediate with a ΔLc of about 55 nm. We assign the third force peak to the unfolding of one of the REJ domains and the next two to the unfolding of the other REJ and I27 domains. (b) Unfolding force histogram for the I27 and REJ domains in the MBP-REJd1,2-I27 construct. In this histogram we did not include the unfolding of the MBP protein. The best fits to Gaussian distributions were obtained with the following parameters: 63 ± 37 pN () and pN (; 47 traces). (c) Force-extension trace of the MBP-REJd1-I27 construct. This example shows the all-or-none unfolding of the MBP protein; in this example there is no unfolding intermediate. The increase in ΔLc is about 100 nm (red double headed arrow). The next two force peaks correspond to the unfolding of REJd1 and I27 domains. The black lines correspond to fits to the WLC equation using a ΔLc of 29 nm. (d) Unfolding force histogram for the I27 and REJ domains in the MBP-REJd1-I27 construct. In this histogram we did not include the unfolding of the MBP protein. There is a single distribution of force peaks with a mean of about 190 pN ( pN, ; 21 traces).
