Stum, short for stumble, is an evolutionarily conserved gene with orthologs in animals from nematodes to mammals. It contains two transmembrane domains and is essential for mechanical sensing in a specific subpopulation of Drosophila proprioceptive neurons that sense joint angles. These neurons' dendrites are stretched by joint movements, and Stum is involved in transducing these mechanical stimuli [1]. It is also associated with the mechanotransduction pathway, as the stum-expressing neurons express the mechanosensory channel NOMPC, and in nompC mutants, responses to joint position are abolished [3].

In Drosophila, a mutant stum 9-3 was initially thought to affect Stum but was later found to be a new allele of O-fut1. This mutant impacts the proliferation and differentiation of Drosophila adult intestinal stem cells through the conserved Notch signaling pathway, upstream of the S2 cleavage of the Notch receptor [2].

In summary, Stum plays a crucial role in mechanical sensing in proprioceptive neurons in Drosophila, and its study, especially through Drosophila genetic models, helps in understanding the molecular mechanisms underlying proprioception. Although no KO/CKO mouse models related to Stum are mentioned in the provided references, the Drosophila models offer insights into its functions, which could potentially be relevant for understanding similar processes in mammals.