Complex sentence: Phosphatidylserine (abbreviated Ptd-L-Ser or PS) is an important phospholipid membrane component (i.e. component of the cell membrane) which plays a key role in cell cycle signaling, specifically in relationship to apoptosis.
Split into simpler sentences: Phosphatidylserine (abbreviated Ptd-L-Ser or PS) is an important Membrane lipid (i.e. component of the cell membrane). It plays a key role in cell cycle signaling, specifically in relationship to apoptosis.