Enables hormone receptor binding activity; long-chain fatty acid binding activity; and long-chain fatty acid transporter activity. Involved in long-chain fatty acid transport and positive regulation of cold-induced thermogenesis. Acts upstream of or within several processes, including brown fat cell differentiation; cellular response to lithium ion; and negative regulation of nitrogen compound metabolic process. Located in cytoplasm and nucleus. Is expressed in several structures, including adipose tissue; central nervous system; genitourinary system; gut; and heart. Orthologous to human FABP4 (fatty acid binding protein 4). [provided by Alliance of Genome Resources, Apr 2022]