To investigate the role of progesterone receptor membrane component 1 (PGRMC1) in oocyte maturation in the half-smooth tongue sole (PGRMC1 from the ovary using homology cloning and rapid amplification of cDNA ends methods. The full-length cDNA of was 1335 bp long with an open reading frame of 546 bp encoding a 181 amino acid preprohormone with a deduced molecular mass of 20.64 kDa and a theoretical isoelectric point of 4.67. The precursor was a single transmembrane protein with an N-terminal transmembrane domain. The predicted transmembrane domain was located at positions 13-35 of the deduced PGRMC1 protein. Sequence alignment of the PGRMC1 precursor protein with corresponding sequences from other species revealed that the highest identity (82.87%) was with the PGRMC1 from (81.22%). In a phylogenetic analysis, the PGRMC1 clustered with its counterparts in the Cyprinodontiformes and Tetraodontiformes. The transcript levels of were high in the ovary, moderate in the liver and brain, and low in other tissues. We also monitored changes in transcript levels in the pituitary, brain, and ovary at different ovarian developmental stages. The mRNA levels increased sharply in the brain at stage Ⅲ, remained at high levels until stage V, and then decreased at stage VI. In the pituitary, the transcript levels of increased to peak at stage V and decreased significantly after ovulation (stage VI). Similarly, in the ovary, the levels increased gradually to peak at stage V and then decreased markedly after spawning (stage VI). Taken together, our results shed light on the role of PGRMC1 in oocyte maturation and in regulating reproductive endocrine function in .