Phosphatidylserine is associated with what charge at pH 7?

Phosphatidylserine is a phospholipid that contains a serine amino acid as its polar head group. At physiological pH, which is around 7, the serine group contributes both a carboxyl group and an amino group to the overall charge of the phosphatidylserine molecule.

The carboxyl group (from the serine) typically has a negative charge at this pH due to the dissociation of its proton, while the amino group can be positively charged depending on its protonation state. However, in the case of phosphatidylserine, the overall charge is primarily determined by the deprotonated carboxyl group. The amino group's positive charge does not fully balance the negative charge from the carboxyl group, leading to an overall net charge of -1 at pH 7.

This makes phosphatidylserine anionic, which is important for its roles in cellular signaling, apoptosis, and its interaction with proteins. The understanding of this specific charge at physiological conditions is crucial for comprehending its biological functions and interactions within cellular membranes.