We purified a novel protein with a molecular mass of 34 kDa from the Sarcophaga larval fat body. This protein, named AFP (anterior fat body protein), was restricted almost exclusively to the anterior fat body. The AFP content decreased after pupation on disintegration of the fat body tissue. cDNA analysis revealed that this protein consists of 306 amino acid residues and exhibits significant structural similarity with mBmnmlian regu-calcin (senescence marker protein-30), a calcium-binding liver protein. However, AFP did not seem to exhibit strong affinity with calcium. These results suggested that a seemingly uniform fat body tissue exhibits a regional difference in its function along the anterior-posterior axis