Eif2s3x encodes subunit three of eukaryotic translation initiation factor 2, regulating the rate of protein translation [1]. It escapes X-inactivation in both humans and mice, and is thus potentially significant in understanding X-linked gene dosage balance and its impact on biological processes [1].

In mouse studies, Eif2s3x mRNA shows sexually dimorphic expression, being higher in females than males in developing and adult brains as well as adult liver [1]. Females had significantly higher Eif2s3x mRNA levels in the cortex, hippocampus, and paraventricular nucleus [1]. However, the sex difference in Eif2s3x transcription may be offset by the male-specific Y-linked homologue Eif2s3y, which is expressed in similar brain regions [1]. The sex difference in Eif2s3x transcript is not preserved at the protein level [1]. Also, transgenic overexpression of Eif2s3x can replace the function of Eif2s3y in male mice with limited Y chromosome genes, allowing for spermatogenesis and assisted reproduction, although they had testicular defects [2,3].

In conclusion, Eif2s3x plays a role in protein translation regulation and exhibits sexually dimorphic mRNA expression in mice, which may be related to sex-related biological differences. Studies using mouse models with altered Eif2s3x expression have provided insights into its function in spermatogenesis and the potential role in testicular development and male reproduction.