Plays a role in the regulation of inhibitory synapse formation and function by being involved in maintening gamma-aminobutyric acid receptors (GABAARs) clustering and their associated scaffold proteins at inhibitory synaptic sites. Acts in concert with NLGN2 to recruit or stabilize GABAARs. Interacts with GABA(A) receptor subunits (PubMed:28279354). Interacts with GABRB3 (By similarity). Interacts with GABRA2 (By similarity). Interacts with GABRG2 (By similarity). Interacts with GABRA1 (PubMed:28279354). Identified in a complex of 720 kDa composed of LHFPL4, NLGN2, GABRA1, GABRB2, GABRG2 and GABRB3 (PubMed:28279354). Interacts with NLGN2; leading to mutual regulation of protein level and synaptic clustering (By similarity). Specifically localizes to inhibitory postsynaptic sites (PubMed:29742426). Colocalizes with GPHN, GABRG2 and NLGN2 at inhibitory postsynaptic sites (PubMed:29742426, PubMed:28978485). Belongs to the LHFP family.