Gnaq, one of Guanine nucleotide-binding protein alpha subunits, was isolated from cellular nucleus extracts of oyster Crassostrea hongkongensis gills with biotin-labeled ChHsc70 promoter by means of DNA-affinity purification, and preliminarily identified with mass spectrometry analysis. ChGnaq mRNA depletion by RNAi technique led to clear reduction in ChHsc70 mRNA expression of C hongkongensis hemocytes. Correspondently, ChGnaq over-expression in heterologous HEK293T cells correlated with elevated expression activation of ChHsc70 promoter. Quantitative real time PCR analysis showed that both ChHsc70 and ChGnaq transcriptions were responsive to external physical/chemical stresses by heat, CdCl2 and NP. This suggested a plausible association between ChHsc70 and ChGnaq in the stress-induced genetic regulatory pathway. This study discovered a positively regulatory role of ChGnaq in controlling ChHsc70 transcription of C hongkongensis, and conduced to a better understanding of the regulatory mechanisms in control of Hsc70 transcription. (C) 2018 Elsevier Inc. All rights reserved.