Monné M, Nilsson I, Johansson M, Elmhed N, von Heijne G
Department of Biochemistry, Stockholm University, Stockholm, S-106 91, Sweden.
J Mol Biol. 1998 Dec 11;284(4):1177-83. doi: 10.1006/jmbi.1998.2218.
We have studied the effects of single charged residues on the position of a model transmembrane helix in the endoplasmic reticulum membrane using the glycosylation mapping technique. Asp and Glu residues cause a re-positioning of the C-terminal end of the transmembrane helix when placed in the one to two C-terminal turns but not when placed more centrally. Arg and Lys residues, in contrast, have little effect when placed in the two C-terminal turn but give rise to a more substantial shift in position when placed 9-11 residues from the helix end. We suggest that this difference between the effects of positively and negatively charged residues can be explained by the so-called snorkel effect, i.e. that the very long side-chains of Arg and Lys can reach up along the transmembrane helix to allow the terminal, charged moiety to reside in the lipid headgroup region while the Calpha of the residue is positioned well below the membrane/water interface.
我们使用糖基化定位技术研究了单个带电残基对内质网膜中模型跨膜螺旋位置的影响。当Asp和Glu残基位于跨膜螺旋C末端的一到两个转角处时，会导致跨膜螺旋C末端重新定位，但位于更中心位置时则不会。相比之下，Arg和Lys残基位于C末端的两个转角处时影响较小，但当位于距螺旋末端9 - 11个残基处时，会导致位置发生更显著的移动。我们认为，带正电和带负电残基效应之间的这种差异可以用所谓的“通气管效应”来解释，即Arg和Lys非常长的侧链可以沿着跨膜螺旋向上延伸，使末端带电部分位于脂质头部区域，而残基的α碳原子则位于膜/水界面下方。
