Amino Acids: Phosphorylation

How many phosphorylation sites does the MGHYT peptide sequence have?

Which of the following peptide sequences would contain the most phosphate once fully phosphorylated?

Several peptide sequences were incubated in the presence of ATP containing radioactive P³² and a kinase-specific to the peptides studied. Which of the following peptide sequences would have the most radioactive activity after incubation?

S249 in the extracellular domain of a receptor tyrosine kinase is phosphorylated leading to a conformational change in the protein and subsequent activation of a second messenger cascade. Substitution of S246 with which of the following amino acids would still allow for the generation of a second messenger cascade by a receptor tyrosine kinase?

ω-secretase a specialized type of protease is activated by phosphorylation of a serine residue within a conserved activation loop. Which of the following amino acids if substituted for serine would lead to an ω-secretase that couldn’t be activated?

SMURF is a homotrimeric protein consisting of a catalytic loop, ligand binding site, and activation domain which has a peptide sequence of LYGAD. Phosphorylation of the activation domain causes a conformational change in the protein and subsequently results in a shift of SMURF from its inactive homotrimeric form into its active monomeric form. Which of the following mutations in the activation domain would result in a protein that is always in its active form? 

Dephosphorylation of phospholamban (PLN) causes PLN to associate with sarcoplasmic reticulum calcium ATPases (SERC) within myocytes impairing their normal function ultimately resulting in decreased cardiac contractility. Scientists attempting to study the impact of PLN on SERC function and cardiac contractility generated mice with mutant PLN proteins by altering the S17 residue. Which of the mutant mice would be expected to have the lowest cardiac contractility?