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Figure 5 | Biology Direct

Figure 5

From: Not all transmembrane helices are born equal: Towards the extension of the sequence homology concept to membrane proteins

Figure 5

Z-score histograms of the functional α-helices, functional TM-helices (SCOP/UniProt-derived), membrane anchors and signal anchors. The z-score histograms for the functional TM-helices (SCOP-derived; Figure 5A and UniProt-derived; Figure 5B), membrane anchors (Figure 5C) and signal anchors (Figure 5D) are shown. The functional TM-helix sets have a characteristics long-tailed, symmetrical and unimodal shape histogram. On the other hand, the histograms of the membrane and signal anchor sets have a left-skewed long-tailed non-unimodality shape. This is suggestive of multiple populations. The two vertical dotted lines define a twilight zone between the functional TM-helices and the anchors based on the z-score thresholds of -7.84 and -3.29 that are calculated from f = 1.980 and f = 1.282 respectively via equation (4).

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