Scyl2, short for SCY1-like protein 2, is a member of the SCY1-like pseudokinase family. It is involved in multiple crucial biological processes. In eukaryotes, it plays a role in protein transport between organelles, specifically in clathrin-mediated vesicle trafficking [4,6]. In the nervous system, it suppresses excitotoxicity during brain development, and is also related to secretory protein trafficking [2,3].

Scyl2 knockout mice have excess prenatal mortality, and survivors show severe neurological dysfunction [2,3]. In humans, bi-allelic loss-of-function variants in SCYL2 are associated with arthrogryposis multiplex congenita-4 (AMC4), characterized by severe arthrogryposis, corpus callosum agenesis, epilepsy, and often early death [2,5].

In plants like rice, SCYL2 is involved in phytosterol accumulation, regulating plant growth and response to salt stress. Mutations lead to stunted growth, while overexpression results in larger leaves, taller plants, and better salt-stress tolerance [1]. In Arabidopsis, its homologs are essential for plant cell growth and root hair development [4].

In conclusion, Scyl2 is essential for normal biological functions in both animals and plants. In animals, it is crucial for nervous system development and function, with its loss-of-function linked to severe neurodevelopmental disorders like AMC4. In plants, it plays a significant role in growth regulation and stress response. Studies using knockout models have been instrumental in revealing these functions, providing insights into the underlying mechanisms and potential implications for related diseases and crop improvement.