Given below is the hydropathy plot of a monomeric transmembrane protein. How many transmembrane $\alpha$-helices are present in the protein?
To determine the number of transmembrane $\alpha$-helices present in the protein based on the hydropathy plot, we need to follow these steps:
Understand the Hydropathy Plot: The hydropathy plot shows the hydrophobic (above 0) and hydrophilic (below 0) regions of a protein sequence. Transmembrane $\alpha$-helices are generally hydrophobic and will appear as peaks above a threshold line in a hydropathy plot.
Identify the Threshold for Transmembrane Helices: A common threshold used to identify transmembrane helices is a hydropathy index of around +20 kJ/mol.
Analyze the Plot: By examining the given plot, notice there is one prominent peak that crosses the +20 kJ/mol threshold, indicating a hydrophobic region likely corresponding to a transmembrane $\alpha$-helix.
Conclusion: Based on the analysis, the plot suggests there is 1 transmembrane $\alpha$-helix in the protein.
Therefore, the correct answer is 1.
Important Questions from Protein Structure Folding Alpha Helix
- A 25 amino acid $\alpha$-helical protein is spanning the thickness of a mammalian cell membrane. Using the average dimensional parameters of a typical $\alpha$-helix, the thickness of the membrane will be ________ $\text{\AA}$ (rounded off to one decimal place).
The following diagram represents energy states of different protein folding steps, which includes-
1. Folded
2. Transition
3. Molten globule
4. Unfolded
Find the correct match of folding steps (1 to 4) with the energy state (P to S) in the diagram.- In a $\alpha$-helix, the R-groups on the amino acid residues
- Which one of the following pairs of amino-acids in the protein has high propensity to take up the $\alpha$-helix conformation?
- Which one of the following closely defines 'Molten Globule' state of a protein?
