Figure 2: Size exclusion chromatography and dynamic light scattering of the Pop5-RPP30 complex. (a) Gel filtration chromatogram of RPP30 alone (solid), RPP30 in the presence of excess Pop5 (dashed), and molecular weight standards (dotted; thyroglobulin (670 kDa), γ-globulin (158 kDa), ovalbumin (44 kDa), myoglobin (17 kDa), and vitamin B12 (1.3 kDa)). The mixture of RPP30 with excess Pop5 yielded one peak corresponding to free Pop5, and a second peak with an apparent mass in excess of that expected for a Pop5-RPP30 heterodimer (39 kDa). (b) Measured hydrodynamic radii of the Pop5-RPP30 complex from dynamic light scattering under varying buffer conditions. The dotted lines indicate the calculated hydrodynamic radii from HYDROPRO [18] for both a heterotetramer or a heterodimer. The smallest hydrodynamic radius is consistent with formation of a heterotetramer [(Pop5-RPP30)2, 3.65 nm].