Endoplasmic reticulum transmembrane protein involved in vesicle-mediated transport, which is required for neutrophil function. Required for vesicle-mediated transport; it is however unclear whether it is involved in early secretory pathway or intracellular protein transport. Acts as a regulator of neutrophil function, probably via its role in vesicle-mediated transport: required for defense against fungal pathogens and for granulocyte colony-stimulating factor (GM-CSF) signaling pathway; possibly by regulating glycosylation and/or targeting of proteins contributing to the viability and migration of neutrophils. Interacts with COPA, COPB2 and COPG2. Ubiquitously expressed. The disease is caused by variants affecting the gene represented in this entry. Belongs to the jagunal family. Experiments in mouse confirm the importance of JAGN1 in neutrophil function with some differences. Mice lacking JAGN1 do not show neutropenia and display increased susceptibility to fungal infections due to defective killing capacity of neutrophil granulocytes. Variant SCNN 'Gln-20' is described as 'Glu-20' (PubMed:25129144). However, based on the substitution described in the paper, it is clearly a 'Gln-20' variant.