SULFONATE BUFFERS AFFECT THE RECOVERY OF MICROTUBULE-ASSOCIATED PROTEINS MAP1 AND MAP2 - EVIDENCE THAT MAP1A PROMOTES MICROTUBULE ASSEMBLY

The influence of two commonly used sulphonate buffers, PIPES and MES, on the in vitro assembly of bovine brain microtubule protein was exami ned. Microtubule assembly was monitored by turbimetry and, after centr ifugation, the polymerised protein was analysed by SDS-PAGE and wester n blotting. Assembly in MES when compared with PIPES resulted in a hig her recovery of microtubule proteins at both pH 6.4 and pH 6.9 and in an altered protein composition. The buffer pH affected the total amoun t of protein polymerised but did not significantly affect the protein composition. At both pH conditions the recovery of HMW-MAPs was marked ly increased in MES buffer and this increase was mostly due to an incr ease in the amount of MAP1.