Component of the Atx2-tyf activator complex which functions in the circadian pacemaker neurons to activate the TYF-dependent translation of per and maintain 24 hour periodicity in circadian behaviors. Within the Atx2-tyf complex, likely to function as a molecular adapter which stabilizes the interaction between Atx2 and the translational regulator tyf. Component of the Atx2-tyf activator complex, composed of Atx2, tyf, pAbp, Lsm12. Interacts with tyf, Atx2 and pAbp. RNAi-mediated knockdown in pigment dispersing factor (Pdf)-expressing clock neurons disrupts circadian locomotor rhythms, with mutants displaying long period locomotor rhythms under constant dark conditions. Enhances the period-lengthening phenotype of tyf mutants. Belongs to the LSM12 family.