The light-harvesting complex (LHC) functions as a light receptor, it captures and delivers excitation energy to photosystems with which it is closely associated, here photosystem I. Binds at least 14 chlorophylls (8 Chl-a and 6 Chl-b) and carotenoids such as lutein and neoxanthin. Emission maxima at 702 nm. The LHC complex consists of chlorophyll a-b binding proteins (PubMed:19139095). Red-emitting heterodimers with LHCA3 and LHCA5 (PubMed:17107674, PubMed:21083539, PubMed:15356385). Binds to carotenoids (PubMed:17326666). Induced by low light (LL) but repressed by high light (HL). Inhibited by cold. The N-terminus of the protein extends into the stroma where it is involved with adhesion of granal membranes and post-translational modifications; both are believed to mediate the distribution of excitation energy between photosystems I and II. Photoregulated by reversible phosphorylation of its threonine residues. Depletion of LHCA3 levels (at protein level). Belongs to the light-harvesting chlorophyll a/b-binding (LHC) protein family.