This family consists of a presumed N-terminal domain that is conserved between dinoflagellate luciferase and luciferin binding proteins. Luciferase is involved in catalysing the light emitting reaction in bioluminescence and luciferin binding protein (LBP) is known to bind to luciferin (the substrate for luciferase) to stop it reacting with the enzyme and therefore switching off the bioluminescence function. The expression of these two proteins is controlled by a circadian clock at the translational level, with synthesis and degradation occurring on a daily basis [1]. However This domain is not the catalytic part of the protein. It has been suggested that this region may mediate an interaction between LBP and Luciferase or their association with the vacuolar membrane [2].

1: Members of a dinoflagellate luciferase gene family differ in synonymous substitution rates. Okamoto OK, Liu L, Robertson DL, Hastings JW; Biochemistry 2001;40:15862-15868. PMID:11747464

2: Three functional luciferase domains in a single polypeptide chain. Li L, Hong R, Hastings JW; Proc Natl Acad Sci U S A. 1997;94:8954-8958. PMID:9256416