FIGURE 2.

Precipitability of ΔN-PAP-III depends on Na⁺ concentrations. A, PAP-III protein was incubated with (+) or without (−) trypsin in 25 mm Tris (pH 7.5) containing 0 (−), 25, and 150 mm NaCl for 2 h (hrs). B, PAP-III protein was treated with trypsin (+) in 25 mm Tris (pH 7.5) containing 150 mm NaCl for 2, 5, and 12 h. Solutions were centrifuged at 20,000 × g, and proteins in supernatant (S) and pellet (P) fractions were resolved by SDS-PAGE followed by Coomassie Brilliant Blue staining. ΔN-PAP-III is precipitated under 0 and 25 mm but not under 150 mm NaCl after 2 h of incubation. ΔN-PAP-III becomes precipitated even in the presence of 150 mm NaCl after 5 h of incubation.