Question

Which of the following is untrue regarding Prediction of Helical Membrane Proteins?

(a) For membrane proteins consisting of transmembrane α–helices, these transmembrane helices are predominantly hydrophobic with a specific distribution of positively charged residues

(b) The α-helices generally run perpendicular to the membrane plane

(c) The α-helices generally run parallel to the membrane plane

(d) The α-helices have an average length between seventeen and twenty-five residues

I had been asked this question in exam.

I'd like to ask this question from Secondary Structure Prediction for Transmembrane Proteins in portion Secondary Structure Prediction of Bioinformatics

Answer 1

Right option is (c) The α-helices generally run parallel to the membrane plane

The explanation is: The hydrophobic helices are normally separated by hydrophilic loops with average lengths of fewer than sixty residues. The residues bordering the transmembrane spans are more positively charged. Another feature indicative of the presence of transmembrane segments is that residues at the cytosolic side near the hydrophobic anchor are more positively charged than those at the lumenal or periplasmic side. This is known as the positive-inside rule.