Langford G M
J Ultrastruct Res. 1983 Oct;85(1):1-10. doi: 10.1016/s0022-5320(83)90111-9.
The length and appearance of microtubule-associated proteins (MAPs) on microtubules reconstituted in vitro have been investigated by the negative-staining technique. We found that uranyl acetate (UA) causes the normally extended MAPs on microtubules to coil up into globular projections 7-10 nm in length. This perturbation occurred if the microtubules reacted with UA before they became adsorbed to the grid surface. If the microtubules were adsorbed to the grid surface before staining, the MAPs remained as extended, filamentous molecules, 35-40 nm in length. Glutaraldehyde also caused MAPs to coil into globular structures. In the altered, globular configuration, MAPs served to crosslink pairs of microtubules. In the normal filamentous configuration, MAPs were never seen to crosslink pairs of microtubules. Therefore, we concluded that MAPs do not function as crosslinking proteins between microtubules.
通过负染技术研究了体外重组微管上微管相关蛋白（MAPs）的长度和外观。我们发现醋酸铀（UA）会使微管上正常伸展的MAPs卷曲成长度为7 - 10纳米的球状突起。如果微管在吸附到网格表面之前与UA反应，就会发生这种扰动。如果微管在染色前吸附到网格表面，MAPs则保持为伸展的丝状分子，长度为35 - 40纳米。戊二醛也会使MAPs卷曲成球状结构。在改变后的球状构型中，MAPs起到交联微管对的作用。在正常的丝状构型中，从未观察到MAPs交联微管对。因此，我们得出结论，MAPs不作为微管之间的交联蛋白发挥作用。
