The primary structure of proteins A and B are listed below A

The primary structure of proteins A and B are listed below. Assume each protein is 100 amino acids in length (full length not shown). Also assume the molecular weight of each amino acid is equal. Predict which protein would have the greater probability of having a higher overall molecular weight in vivo? Explain your rationale. Protein A Gln-Ile-Thr-Gln-Ala-Ser-Val-Asn-Met-Val-Gly Protein B Asn-Val-Ser-Asn-Ile-Thr-Trp-Gln-His-Ser-Tyr

Solution

Answer:

Protein B will have a greater probability of having a higher probability in vivo.

Protein Post-Translational Modification (PTM) increases the functional variety of the proteome by covalent bonding of functional groups and proteins. These modifications caused by phosphorylation, glycosylation, ubiquitination, nitrosylation, methylation, acetylation and lipidation.

Protein B has amino acid composition which are more prone to the common posttranslational modification in vivo, compared to the amino acid composition of protein A.

Examples: N-linked glycosylation = Asn

Phosphorylation = Ser, Thr, His and Tyr

Sulfation = Tyr