进入位点

The 20S catalytic core of the 26S proteasome has the shape of a barrel made of four rings which are composed of seven differentαsubunitsα_1-α_7 at two outer rings and seven differentβsubunitsβ_1-β_7 at two inner rings at which the catalytic sites locate. Three of theβsubunits contain proteolyses sites, which are sequestered in the hollow interior of the 20S particle. Substrates enter the 20S through a narrow channel formed by theβsubunits, whose N-termini, depending on their conformation, can either obstruct or allow substrate entry and thus function as a gate. This entry channel is narrow and only permits passage of unfolded, linearized polypeptides.

哺乳动物26S蛋白酶体是由一个20S催化颗粒(catalytic particle，CP)和两个19S调节颗粒(regulatory particle，RP)组成的ATP(adenosine-triphosphate，ATP)依赖性蛋白水解酶复合体。20S CP是26S蛋白酶体的催化核心，它是由4个圆环堆叠形成的桶状复合物，其中两侧外环每个环是由α_1-α_7亚基组成，两个内环每个环是由β_1-β_7亚基组成，4个环的中央形成一个狭窄的内腔。2个β内环形成了20S CP的催化中心空腔，其内壁为催化活性位点所在地；外侧α环中心的孔道是底物到达催化中心空腔的通道，一般被α亚基上的N末端所封闭，阻止胞内非目的靶蛋白进入20S CP内被降解破坏。

Since a dipeptide is formed, translation initiation is not affected, nor is the first step of elongation―the binding of a charged tRNA in the A site and the formation of a peptide bond.

既然能够形成二肽，说明翻译的起始不会受到影响，同时，延伸的第一步即荷载的tRNA进入A位点并形成肽键也不会受到影响。

Toward this end, we evaluated small hairpin interfering RNAs targeting the conserved internal ribosome entry site element of the HCV genome for their ability to control gene expression in human cells and animals.

为此，我们评价了针对HCV基因组保守序列——内核糖体进入位点的小发卡RNA在人类细胞和动物体内控制基因表达的能力。

An internal ribosome entry site was found in WSSV and subsequently confirmed,which would be helpful to realize the translation regulation of WSSV genes, and also could be used directly.

试验还证实了1个内部核糖体进入位点，它不仅有利于在翻译水平阐明WSSV基因的调控机制，而且具有应用价值。

Then the combinant plasmid was conducted into ACC-2 cell by electroporation. ACC-2 cells stably expressing CD was obtained by 10-day positive selection with 400 μg/mL G418. Total RNA was extracted and the expression of the CD gene in transfected ACC-2 cells was identified by RT-PCR. RESULTS: PCR yielded a fragment of l280bp and CD was verified by sequence analysis.

测序正确后，将其亚克隆到质粒表达载体pIRES中，构建以内部核糖体进入位点相连的CD基因的质粒表达载体pIRES-CD，采用电穿孔法，以质粒表达载体转染ACC-2细胞，用400μg/mL的G418筛选10d，获得稳定表达CD基因的ACC-2细胞系，提取该细胞的总RNA，用RT-PCR检测CD基因的表达。

Time constants do not increase but the weights of the fittings concentration de pendently enhance as the external Ba2+ concentration augments. So the inac tivati on becomes faster and faster as the external Ba2+ concentration increases. Time constants decrease and the weights of the fittings concentration dependently enh ance as the external Ba2+ concentration augments when external Ba2+ concentratio n (10 or 100 μmol/L) is higher. So the inactivation becomes faster and faster. It is showed that Ba2+ can go deeper in IRK1-T from the surface of the ch annel a s external Ba2+ concentration increases.

三级指数拟合表明：细胞外Ba2+低浓度(1和3 μmol/L)时，Ba2+与K+相互竞争同一结合位点，随着Ba2+浓度的增加，时间常数不增加但拟合的权数却浓度依赖性增加，所以失活过程随Ba2+浓度的增加越来越快；细胞外Ba 2+高浓度(10和100 μmol/L)时，时间常数随Ba2+浓度的增加而减少，拟合的权数却浓度依赖性减少，失活过程也越来越快，说明Ba2+作用位点由通道的表面部位进入通道更深的地方。

Time constants do not increase but the weights of the fittings concentration de pendently enhance as the external Ba2+ concentration augments. So the inac tivati on becomes faster and faster as the external Ba2+ concentration increases. Time constants decrease and the weights of the fittings concentration dependently enh ance as the external Ba2+ concentration augments when external Ba2+ concentratio n (10 or 100 μmol/L) is higher. So the inactivation becomes faster and faster. It is showed that Ba2+ can go deeper in IRK1-T from the surface of the ch annel a s external Ba2+ concentration increases. CONCLUSION: Two diffe rent mechanisms for external Ba2+ blocking exist.

三级指数拟合表明：细胞外Ba2+低浓度(1和3 μmol/L)时，Ba2+与K+相互竞争同一结合位点，随着Ba2+浓度的增加，时间常数不增加但拟合的权数却浓度依赖性增加，所以失活过程随Ba2+浓度的增加越来越快；细胞外Ba2+高浓度(10和100 μmol/L)时，时间常数随Ba2+浓度的增加而减少，拟合的权数却浓度依赖性减少，失活过程也越来越快，说明Ba2+作用位点由通道的表面部位进入通道更深的地方。

Time constants do not increase but the weights of the fittings concentration de pendently enhance as the external Ba2+ concentration augments. So the inac tivati on becomes faster and faster as the external Ba2+ concentration increases. Time constants decrease and the weights of the fittings concentration dependently enh ance as the external Ba2+ concentration augments when external Ba2+ concentratio n (10 or 100 μmol/L) is higher. So the inactivation becomes faster and faster. It is showed that Ba2+ can go deeper in IRK1-T from the surface of the ch annel a s external Ba2+ concentration increases. CONCLUSION: Two diffe rent mechanisms for external Ba2+ blocking exist.

三级指数拟合表明：情绪细胞外Ba2+低浓度(1和3 μmol/L)时，Ba2+与K+相互竞争同一结合位点，随着Ba2+浓度的增加，时间常数不增加但拟合的权数却浓度依赖性增加，所以失活过程随Ba2+浓度的增加越来越快；情绪细胞外Ba2+高浓度(10和100 μmol/L)时，时间常数随Ba2+浓度的增加而减少，拟合的权数却浓度依赖性减少，失活过程也越来越快，说明Ba2+作用位点由通道的表面部位进入通道更深的地方。

In the normal strain, a drug molecule binds tightly to the site, but in the drug-resistant strain, it approaches and then drifts slowly away.

在正常菌株，药物分子能够与该位点紧密结合，但是在耐药菌株，药物进入此位点然后慢慢的漂移。

It is possible to preparing neutralizing MAb which target to active region of Stx2 by synthetical B cell epitope peptides. At present, the crystal structure of the compound of Stx2 and its ligand adenines has been resolved, and the active site of Stx2 is definite, which is the seventy-seventh amino acids, Ganimalon, of Stx2 A1 fragment.

Stx2通过B亚基与受体Gb3结合后，进入细胞，在弗林蛋白酶(一种钙敏感的丝氨酸蛋白酶)作用下A亚基被裂解为A1和A2两个片段，A1片断经内质网进入细胞质暴露毒性活性位点―A1片段发挥N-糖苷酶活性，导致真核细胞蛋白质合成的终止，最终导致细胞的死亡。

Neither the killing of Mr Zarqawi nor any breakthrough on the political front will stop the insurgency and the fratricidal murders in their tracks.

在对危险的南部地区访问时，他斥责什叶派民兵领导人对中央集权的挑衅行为。

In fact,I've got him on the satellite mobile right now.

实际上 我们已接通卫星可视电话了