7月16日Science网站发表美国俄勒冈健康与科学大学Eric Gouaux实验室
（同样属“生命科学领域的最高荣誉之一”HHMI）的一篇论文，该论文以较
高的分辨率解析出了ApcT蛋白质晶体结构。这个蛋白质的氨基酸序列和功能
与施一公解析的AdiC相似，通过比较两个蛋白质晶体结构，Gouaux论文的观
点与Miller在Nature发表的论文的结论一样，认为施一公的晶体结构搞错了
一圈，导致一些重要氨基酸残基都不在正确的位置上。

Structure and Mechanism of a Na+ Independent Amino Acid Transporter
Paul L. Shaffer, April Goehring, Aruna Shankaranarayanan, and Eric Gouaux
Published online July 16 2009; 10.1126/science.1176088 (Science Express Reports)

"The arginine/agmatine antiporter from Escherichia coli
(19) (AdiC) is a member of the APC transporter family.
Recently Gao et al. reported its crystal structure (25).
Because ApcT is related to AdiC in amino acid sequence and
in biochemical function, we compared our structure of ApcT,
determined at 2.35 ? resolution, to the structure of AdiC,
solved at ~3.6 ? resolution (PDB code 3H5M). As
anticipated from the relationships in amino acid sequence, the
protein folds of ApcT and AdiC are similar. We found
significant discrepancies, however, between the
superpositions of the ApcT and AdiC structures and the
independently aligned amino acid sequences in the
transmembrane segments 6, 7, and 8 (figs. S11 and S12).
Analysis of the structures and the sequence alignments leads
us to conclude that in the AdiC structure, in the regions of
TMs 6, 7, and 8 and perhaps to the C terminus, the amino
acid sequence is off register by several amino acid residues
relative to ApcT, beginning at the “loop” between TMs 5 and
6. This means that many residues after the end of TM5,
including key residues such as Glu208, Tyr239 and Trp293,
are “frame shifted” by ~4 residues or about one turn of a-
helix (25) (figs. S11 to S13). Because of this frame-shift, we
have not used the AdiC structure in our analysis of APC
transporters."