Plays an essential role in the Tl receptor signaling pathway that establishes embryonic dorsoventral polarity; the signal directs import of dl into ventral and ventrolateral nuclei, thereby establishing dorsoventral polarity. Tub recruits pll to the plasma membrane and protein-protein interaction activates pll. ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Interacts (via Death domain) with tub (via Death domain). Interacts with Pellino (Pli). Associates with the plasma membrane during interphase syncytial blastoderm embryos, more specifically at the membrane invaginations around the nuclei. Expressed both maternally and zygotically with low levels of expression throughout the life cycle. Belongs to the protein kinase superfamily. TKL Ser/Thr protein kinase family. Pelle subfamily. Truncated C-terminus.