Boyd D, Manoil C, Beckwith J
Department of Microbiology and Molecular Biology, Harvard Medical School, Boston, MA 02115.
Proc Natl Acad Sci U S A. 1987 Dec;84(23):8525-9. doi: 10.1073/pnas.84.23.8525.
The topology of the integral membrane protein MalF, which is required for maltose transport in Escherichia coli, has been analyzed using fusions of alkaline phosphatase (EC 3.1.3.1). The properties of such fusion strains support a MalF structure previously proposed on theoretical grounds. Several transmembrane segments within MalF can act as signal sequences in exporting alkaline phosphatase. Other transmembrane sequences, in conjunction with cytoplasmic domains, can stably anchor alkaline phosphatase in the cytoplasm. Our results suggest that features of the amino acid sequence (possibly the positively charged amino acids) of the cytoplasmic domains of membrane proteins are important in anchoring these domains in the cytoplasm. These studies in conjunction with our earlier results show that alkaline phosphatase fusions to membrane proteins can be an important aid in analyzing membrane topology and its determinants.
整合膜蛋白MalF是大肠杆菌中麦芽糖转运所必需的，利用碱性磷酸酶（EC 3.1.3.1）融合蛋白对其拓扑结构进行了分析。此类融合菌株的特性支持了先前基于理论提出的MalF结构。MalF中的几个跨膜片段可作为输出碱性磷酸酶的信号序列。其他跨膜序列与细胞质结构域一起，可将碱性磷酸酶稳定锚定在细胞质中。我们的结果表明，膜蛋白细胞质结构域的氨基酸序列特征（可能是带正电荷的氨基酸）对于将这些结构域锚定在细胞质中很重要。这些研究与我们早期的结果表明，膜蛋白的碱性磷酸酶融合蛋白在分析膜拓扑结构及其决定因素方面可能是一个重要的辅助手段。
