Morris S A, Schröder S, Plessmann U, Weber K, Ungewickell E
Max-Planck Institute for Biochemistry, Martinsried, Germany.
EMBO J. 1993 Feb;12(2):667-75. doi: 10.1002/j.1460-2075.1993.tb05700.x.
Binding of AP180 to clathrin triskelia induces their assembly into 60-70 nm coats. The largest rat brain cDNA clone isolated predicts a molecular weight of 91,430 for AP180. Two cDNA clones have an additional small 57 bp insert. The deduced molecular weight agrees with gel filtration results provided the more chaotropic denaturant 6 M guanidinium thiocyanate is substituted for the weaker guanidinium chloride. The sequence and the proteolytic cleavage pattern suggest a three domain structure. The N-terminal 300 residues (pI 8.7) harbour a clathrin binding site. An acidic middle domain (pI 3.6, 450 residues), interrupted by an uncharged alanine rich segment of 59 residues, appears to be responsible for the anomalous physical properties of AP180. The C-terminal domain (166 residues) has a pI of 10.4. AP180 mRNA is restricted to neuronal sources. AP180 shows no significant homology to known clathrin binding proteins, but is nearly identical to a mouse phosphoprotein (F1-20). This protein, localized to synaptic termini, has so far been of unknown function.
AP180与网格蛋白三脚蛋白复合体结合可诱导其组装成60 - 70纳米的衣被。分离得到的最大的大鼠脑cDNA克隆预测AP180的分子量为91,430。两个cDNA克隆有一个额外的57 bp小插入片段。如果用更强的变性剂6 M硫氰酸胍替代较弱的胍盐酸盐，推导得到的分子量与凝胶过滤结果相符。序列和蛋白水解切割模式表明其具有三结构域结构。N端的300个残基（pI 8.7）含有一个网格蛋白结合位点。一个酸性的中间结构域（pI 3.6，450个残基），被一个由59个残基组成的不带电荷的富含丙氨酸的片段打断，似乎是AP180异常物理性质的原因。C端结构域（166个残基）的pI为10.4。AP180 mRNA仅限于神经元来源。AP180与已知的网格蛋白结合蛋白没有显著同源性，但与一种小鼠磷蛋白（F1 - 20）几乎相同。这种定位于突触末端的蛋白，其功能至今未知。
