Cloning and expression analysis of γ-aminobutyrate type A receptor-associated protein (GABARAP) in Asiatic hard clam, Meretrix meretrix

• The full-length cDNA and genomic DNA of GABARAP in M. meretrix was newly identified.
• MmGABARAP was significantly highly expressed in hepatopancreas among other tissues.
• MmGABARAP was correlated with the immunological response in clams.

The γ-aminobutyrate type A receptor-associated protein (GABARAP) is tightly connected with innate immunologic responses due to its implication in autophagic and apoptotic processes. In the present study, the full-length cDNA encoding GABARAP (designated MmGABARAP) was first cloned from Asiatic hard clam Meretrix meretrix using the rapid amplification of cDNA ends approach and expression sequence tag analysis, and its genomic DNA has also been cloned. Its full-length cDNA is 920 bp with a 354 bp open reading frame encoding a protein of 117 aa. Its genomic DNA sequence comprises 5826 bp, containing three exons and two introns. Real-time quantitative PCR analysis revealed that MmGABARAP was constitutively expressed in all the tissues examined, with the highest expression level in the hepatopancreas, and was up-regulated in the hepatopancreas and hemocytes after bacterial challenge. These results suggested that MmGABARAP could respond to bacterial challenge and might play a vital role in the innate immune system against pathogens in clams.