Salt-dependent assembly curves of tail fragments. Salt-dependent assembly curves of mutant tail fragments show some variability compared with wild type. First, 100 μg each tail fragment were dialyzed into different NaCl concentrations, ranging from 50 mM to 500 mM (x-axis). After dialysis, the percent solubility (y-axis) of each protein at each salt concentration was determined. Solubility curves were generated for each mutant tail (solid line with squares) compared with wild type (dashed line with circles). Lines shown are the averaged values with dots representing the experimental values. The R1165C mutant protein (panel A) had higher solubility through the physiologic salt concentrations and then became similar to wild type. The E1841K mutant protein (panel C) appeared less soluble than wild type throughout most concentrations tested. The D1424N (panel D) and R1933Stop (panel B) mutant proteins had very similar solubility profiles throughout most concentrations.