NPHS1 protein, also known as nephrin, is a type-1 transmembrane protein primarily found in renal tissues, specifically at the slit diaphragm of glomerular podocytes. It is a member of the immunoglobulin family of cell adhesion molecules and plays a crucial role in the glomerular filtration barrier, functioning as an ultrafilter to exclude albumin and other plasma macromolecules from urine. Mutations in the NPHS1 gene can lead to Finnish-type congenital nephrosis 1, characterized by severe proteinuria and loss of the slit diaphragm and foot processes.