尽管许多生物性的屏障和区隔分界是由基于脂质的膜所形成的，但人们越来越多地了解到，在细胞内还有基于蛋白质的区室可作为与外界隔绝的环境。许多细菌细胞中含有这样的微区室，它们将特别的代谢过程（涉及不稳定性或毒性代谢物）进行隔离而起着简单的细胞器的作用。
在2010年1月1日刊的《科学》杂志中，Tanaka 等人报告了在大肠杆菌中隔绝乙醇胺代谢的某一微区室的四种主要蛋白成分的高解析度晶体结构。这一区室可防止乙醛释放到细胞的其它区域，从而减轻了因过多的乙醛而可能造成的毒性影响。尽管这四种蛋白质具有相似的3维交叠，但它们仍然有其独特的结构特征，这可以解释它们在该微区室中所扮演的独特作用：例如在蛋白外壳中设置通过孔隙而进行的分子转运的门径，或与核酸进行结合。（生物谷Bioon.com）
生物谷推荐原始出处：
Science 1 January 2010: DOI: 10.1126/science.1179513
Structure and Mechanisms of a Protein-Based Organelle in Escherichia coli
Shiho Tanaka,1 Michael R. Sawaya,2,3 Todd O. Yeates1,3,4,*
Many bacterial cells contain proteinaceous microcompartments that act as simple organelles by sequestering specific metabolic processes involving volatile or toxic metabolites. Here we report the three-dimensional (3D) crystal structures, with resolutions between 1.65 and 2.5 angstroms, of the four homologous proteins (EutS, EutL, EutK, and EutM) that are thought to be the major shell constituents of a functionally complex ethanolamine utilization (Eut) microcompartment. The Eut microcompartment is used to sequester the metabolism of ethanolamine in bacteria such as Escherichia coli and Salmonella enterica. The four Eut shell proteins share an overall similar 3D fold, but they have distinguishing structural features that help explain the specific roles they play in the microcompartment. For example, EutL undergoes a conformational change that is probably involved in gating molecular transport through shell protein pores, whereas structural evidence suggests that EutK might bind a nucleic acid component. Together these structures give mechanistic insight into bacterial microcompartments.
1 Department of Chemistry and Biochemistry, University of California Los Angeles, 611 Charles Young Drive East, Los Angeles, CA 90095, USA.
2 Howard Hughes Medical Institute, University of California Los Angeles, 611 Charles Young Drive East, Los Angeles, CA 90095, USA.
3 Univeristy of California Los Angeles, Department of Energy Institute for Genomics and Proteomics, 611 Charles Young Drive East, Los Angeles, CA 90095, USA.
4 Molecular Biology Institute, University of California Los Angeles 611 Charles Young Drive East, Los Angeles, CA 90095, USA.
