Steep1, a gene with its function yet to be fully elaborated, was identified as a divergent paralog within suborder Yangochiroptera in the study of positively selected genes in the hoary bat (Lasiurus cinereus) lineage [2]. While its exact function in this context remains unclear, the finding of its divergence in this lineage may suggest its role in the adaptive evolution of these bats, potentially related to the immune and metabolic functions that were prominent among the positively selected genes in this study.

In relation to its potential function, in a different context, STEEP (a related entity, potentially related to Steep1) was found to be a positive regulator of STING signaling. STEEP associated with STING and promoted its trafficking from the endoplasmic reticulum (ER) to the ERGIC/Golgi, where STING signaling occurs. This was achieved through stimulation of phosphatidylinositol-3-phosphate (PtdIns(3)P) production and ER membrane curvature formation, inducing COPII-mediated ER-to-Golgi trafficking of STING. Depletion of STEEP impaired STING-driven gene expression in response to virus infection in brain tissue and in cells from patients with STING-associated diseases [1].

In conclusion, although Steep1's function needs further exploration, the discovery of its divergence in bats may hint at its role in adaptive evolution. Also, the related STEEP's role in STING signaling provides a possible functional framework for understanding Steep1, potentially in relation to immune-related processes and diseases associated with STING dysregulation.