Glucocerebrosidase gene has an alternative upstream promoter, which has features and expression characteristic of housekeeping genes.

Database searches have shown that a part of glucocerebrosidase (GBA) transcripts may originate at an alternative upstream promoter (P2) located 2.6kb upstream of the known (P1) GBA promoter. The putative alternative transcripts contained one or two extra exons (exon −2 or exons −2, −1, respectively), but the first ATG codon and predicted amino-acid sequence are the same as in the transcript from P1. Luciferase assays confirmed promoter activity of both sites in HepG2 cells: the P1 construct exhibited the highest activity of luciferase (17.82±1.10 relative luciferase units), while the P2 construct reached 3.01±0.43 relative luciferase units. Serial 5′ deletions of P2 led to changes in reporter activity, the most prominent decreases were observed in deletion constructs carrying bases −353 to −658, and −353 to −920 (numbered as in NM_001005750.1), respectively. This suggests that the P2 core promoter is contained within the region of −920bp to −1311bp.