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:28978485). Identified in a complex of 720 kDa composed of LHFPL4, NLGN2, GABRA1, GABRB2, GABRG2 and GABRB3 (By similarity). Interacts with GABRB3 (By similarity). Interacts with GABRA2 (By similarity). Interacts with GABRG2 (By similarity). Interacts with GABRA1 (PubMed:28978485). Interacts with NLGN2; leading to mutual regulation of protein level and synaptic clustering (By similarity). Specifically localizes to inhibitory postsynaptic sites (By similarity). Colocalizes with GPHN, GABRG2 and NLGN2 at inhibitory postsynaptic sites (By similarity). Belongs to the LHFP family.