Enables G-protein alpha-subunit binding activity; guanyl-nucleotide exchange factor activity; and tumor necrosis factor receptor binding activity. Involved in several processes, including negative regulation of cell communication; positive regulation of testosterone secretion; and response to melanocyte-stimulating hormone. Located in Golgi medial cisterna and extracellular space. Biomarker of obesity and type 2 diabetes mellitus. Orthologous to human NUCB2 (nucleobindin 2). [provided by Alliance of Genome Resources, Apr 2022]