| DCP1B, a paralog of DCP1A within the conserved mRNA decapping machinery, functions as the essential non-catalytic scaffold that enables DCP2-mediated hydrolysis of the 5' mRNA cap structure, committing transcripts to rapid 5'-3' exonucleolytic degradation by XRN1. Its signature EVH1 domain locks onto DCP2's proline-rich interaction motif to form a stable heterodimer, while auxiliary helical regions position mRNA substrates optimally at the catalytic core for efficient cap removal; this decapping reaction integrates directly into quality control pathways where UPF1 recruits DCP1B/DCP2 complexes to premature termination codon-bearing transcripts during nonsense-mediated decay. DCP1B concentrates within cytoplasmic processing bodies alongside RCK/p54 (DDX6 helicase) and Lsm1-7 ring complexes that circularize mRNA ends to exclude ribosomes and license decay, while mitotic hyperphosphorylation, likely mirroring DCP1A regulation, disrupts these foci to transiently stabilize the transcriptome during chromosome segregation. This cell cycle gating prevents erroneous translation from partially decayed messages when nuclear reassembly demands translational silence. Physiologically, DCP1B maintains proteome homeostasis by clearing aberrant transcripts, buffers stress responses through P-body mediated mRNA sequestration, and supports viral defense by depleting host translation capacity. Dysregulation promotes protein aggregation diseases through stalled decay complexes and enhances viral replication via host transcriptome erosion. |
Lane 1: HepG2, Lane 2: MCF7
