LNX2 (LIGAND OF NUMB PROTEIN X2, PDZ DOMAIN-CONTAINING RING FINGER PROTEIN 1, PDZRN1), which interacts with mammalian Numb and NumbL, contains a RING finger domain, followed by a motif similar to a PTB-binding motif and 4 PDZ domains. Lnx2 and Lnx1 (a proposed relative) are multimodular proteins that bind Numb, a cell fate determinant, through their NPXY motifs. Studies may suggest that Lnx proteins act as molecular scaffolds that promote the aggregation of unrelated, interacting proteins, such as Numb, to definitive subcellular sites. The LNX2 gene maps to chromosome 13q12.2 based on an alignment of the LNX2 sequence with the genomic sequence. Lnx proteins may form large networks by homomeric binding, and their expression patterns overlap with those of the Numb proteins. Furthermore, studies also suggest that the oligomerization of Lnx2 and Numb binding occurs simultaneously.