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 (PubMed:28978485, PubMed:28279354, PubMed:29742426). Acts in concert with NLGN2 to recruit or stabilize GABAARs (PubMed:29742426). Interacts with GABA(A) receptor subunits (PubMed:28279354, PubMed:28978485, PubMed:29742426). Interacts with GABRB3 (PubMed:28978485). Interacts with GABRA2 (PubMed:28978485). Interacts with GABRG2 (PubMed:28978485, PubMed:29742426). Interacts with GABRA1 (PubMed:29742426). Identified in a complex of 720 kDa composed of LHFPL4, NLGN2, GABRA1, GABRB2, GABRG2 and GABRB3 (By similarity). Interacts with NLGN2; leading to mutual regulation of protein level and synaptic clustering (PubMed:29742426, PubMed:28978485). Specifically localizes to inhibitory postsynaptic sites (PubMed:28978485, PubMed:29742426). Colocalizes with GPHN, GABRG2 and NLGN2 at inhibitory postsynaptic sites (By similarity) (PubMed:29742426). Highly expressed in the brain, including the cortex, hippocampus, midbrain, olfactory bulb pona plus medulla (at protein level) (PubMed:26964900, PubMed:28279354, PubMed:29742426). Expressed in the in the cerebellar granular layer and in granular layer. Colocalized with GPHN at inhibitory synapses (PubMed:29742426). Weakly expressed in heart, testis, lung, intestine, vagina, ovary and uterus (PubMed:26964900). Contradictory results have been described and may be due to differences in the methods used for gene disruption (PubMed:28978485, PubMed:29742426). No visible phenotype, mice are viable and fertile until adulthood (PubMed:28978485). However cultured hippocampal neurons from deficient mice shown a dramatic decrease in both amplitude and frequency of miniature inhibitory postsynaptic currents (mIPSC) (PubMed:28978485). In contrast, deficient mice exhibit profound impairment of inhibitory synapse formation, prominent motor behavioral deficits and premature death (PubMed:29742426). Belongs to the LHFP family.