Crandall J E, Fischer I
Department of Developmental Neurobiology, E. K. Shriver Center for Mental Retardation, Waltham, MA 02254.
J Neurochem. 1989 Dec;53(6):1910-7. doi: 10.1111/j.1471-4159.1989.tb09261.x.
The relative levels of microtubule-associated protein 2(MAP2) were determined during postnatal development of the mouse in six different discrete brain regions: cerebellum, cortex, hippocampus, olfactory bulb, brainstem, and hypothalamus. Brain homogenates were electrophoresed on sodium dodecyl sulfate-containing gels and analyzed by immunoblotting with MAP2-specific antibodies. The levels of MAP2 in each region were determined using radiolabeled secondary antibodies and densitometric quantification of the autoradiograms over a range that was determined to have a linear response. The results indicated that in all regions and at all ages there was only one high-molecular-weight polypeptide of MAP2, which did not change in electrophoretic mobility after dephosphorylation. In most regions, the levels of MAP2 increased during the first 2 postnatal weeks. However, there were differences in the time course and relative levels of MAP2 between regions. In addition, all regions of the brain expressed the low-molecular-weight form of MAP2 (MAP2c) that was present at birth as a heterogeneous group of polypeptides with an apparent molecular weight of 70K. Most of the heterogeneity of MAP2c, however, was eliminated after dephosphorylation. The levels of MAP2c decreased dramatically after 2 weeks postnatally, except for the olfactory bulb, where the levels of MAP2c remained relatively high even in adults.
在小鼠出生后的发育过程中，测定了六个不同离散脑区（小脑、皮层、海马体、嗅球、脑干和下丘脑）中微管相关蛋白2（MAP2）的相对水平。将脑匀浆在含十二烷基硫酸钠的凝胶上进行电泳，并用MAP2特异性抗体通过免疫印迹法进行分析。使用放射性标记的二抗和对放射自显影片在确定具有线性响应的范围内进行光密度定量，来测定每个区域中MAP2的水平。结果表明，在所有区域和所有年龄段，MAP2只有一种高分子量多肽，去磷酸化后其电泳迁移率没有变化。在大多数区域，出生后的前两周内MAP2水平升高。然而，不同区域之间MAP2的时间进程和相对水平存在差异。此外，脑的所有区域都表达低分子量形式的MAP2（MAP2c），出生时它以一组表观分子量为70K的异质多肽形式存在。然而，MAP2c的大部分异质性在去磷酸化后消除。出生后2周后，MAP2c水平急剧下降，但嗅球除外，即使在成年后嗅球中MAP2c水平仍相对较高。
