mM PNT (EMD Millipore) and 1 mM PMSF (Sigma-Aldrich) and incubated on ice for 1 hour. The samples were then centrifuged for 1 hour at 100,000 × g and the supernatant fractions were collected as 1% sarkosyl/RIPA-soluble fractions. The insoluble pellets were briefly washed two times with 1% sarkosyl/RIPA buffer, further extracted with 90% formic acid (Sigma-Aldrich) on ice and centrifuged for 1 hour at 100,000 × g to get 1% sarkosyl/RIPA-insoluble/formic acid-soluble fractions.
