Enables Toll-like receptor 4 binding activity and chemoattractant activity. Acts upstream of or within several processes, including I-kappaB phosphorylation; cellular response to interleukin-1; and response to stilbenoid. Located in extracellular space. Is expressed in cerebellum; ileum; liver; reproductive system; and thymus. Orthologous to several human genes including SAA2 (serum amyloid A2). [provided by Alliance of Genome Resources, Apr 2022]