Practice question

LAG-2 encodes Delta-like ligand for LIN-12 and GLP-1 Notch receptors. In early embryo, ABa and MS express GLP-1 while P2 presents LAG-2 and APX-1 to activate GLP-1 in ABp for A-P patterning of pharynx. In gonad, Z1.ppp/Z4.aaa require LAG-2/LIN-12 interaction to decide anchor cell versus ventral uterine fate. Without functional LAG-2, GLP-1 and LIN-12 receptors remain unbound, NICD cleavage fails, downstream targets lag-1 dependent transcription silent. Consequently ABp to ABa transformation and AC/VU defects occur, but fundamentally LIN-12 remains inactive due to absent ligand triggering, revealing ligand-dependent activation mode of Notch signaling in nematode.