Case 2 - Bartter's Syndrome and Protein Structure  University Of Georgia BCMB 3100

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Life works because of proteins; when proteins don’t work, disease typically occurs. Protein function is
dictated by protein structure. Protein structure can be explained through basic chemistry that you
learned in gen chem, e.g., hydrogen bonding.
 Briefly describe Bartter’s syndrome and the role of the gene KCNJ1.
 Explain ion channels and why they are needed by the cell.
 Explain why the potassium ion channel excludes sodium ions but not potassium ions.
 Explain why polar and non-polar residues of the potassium ion channel are distributed as they are.
 Contrast the distribution of amino acids between membrane proteins and cytoplasmic proteins.
 Describe in detail the secondary, tertiary, and quaternary structure of the potassium ion channel.
 Describe how hydrogen bonding gives rise to alpha helical structure. Consider how changes in
amino acid atoms would impact this hydrogen bonding.
 Describe how non-covalent interactions give rise to tertiary and quaternary structure. Consider how
changes in amino acid side chains will impact these structures.
The Story
“Imagine knowing something is wrong with your baby, but medical professionals cannot provide a
diagnosis. Frustrated and scared, you spend every waking moment agonizing about your child’s health
and quality of life; you feel helpless and alone. Nobody seems to understand, and some people even
insist your child is fine and you are overreacting. Deep down, you know there is something wrong. That
is what the Hoffmans experienced after the birth of their son, Ethan.
“Lilia and Daniel Hoffman were elated about the upcoming birth of their baby boy. Their excitement
quickly turned to concern when Lilia began to experience serious complications due to excess amniotic
fluid around the fetus, placing her pregnancy at high-risk. At 36 weeks, Lilia was induced and gave
birth to Ethan, who weighed 6.3 lbs and seemed like a healthy baby boy.
“When he was just 6-weeks old, Ethan began to voluntarily limit his food intake, vomit or spit up
whatever amount he ingested, and always looked tired. He was hospitalized several times for
dehydration and was extremely lethargic, skeletal in appearance, constantly