Question

9. Draw a hydropathy plot of a 330 amino acid long singlepass transmembrane protein that has a TM region beginning at residue 55. Generally, how long would you have to draw the TM region? 17. Describe two examples of membrane protein constraint and why it is important in each system. Draw diagrams.

Answer 1

9) cell membrane thickness is 75A

Ans we assume that transmembrane protein is made up of $\alpha$ helical protein

So in one turn of $\alpha$ helical protein length is 5.4A

So to pass 75A of membrane 5.4x75A=13.88 turn required

And in 1 turn of $\alpha$ helical protein reside 3.6 amino acids

So in 13.88 turn of $\alpha$ helical turn total no. Of amino acid will be 13.88x 3.46=50 residue

So 50 residue required to pass the thickness of cell membrane which start from residue 55 and goes till 55+ 50=105 amino acids long

17) mebrane protein constrain occur to unlike interection as protein is made up of mostly polar and hydrophilic molecule while cell membrane is made up of non polar hydrophobic molecule. So this unfavourable interection make constrain in movement of protein either lateral or transverse movement.

This is important do that there could stability is sea of lipids and also these protein could act as transmembrane protein which allow movement of molecule from outside to inside.

Hope it's clear..thanks