A NOVEL CDNA FROM DROSOPHILA ENCODING A PROTEIN WITH SIMILARITY TO MAMMALIAN CYSTEINE-RICH SECRETORY PROTEINS, WASP VENOM ANTIGEN-5, AND PLANT GROUP-1 PATHOGENESIS-RELATED PROTEINS

The CAP protein family is made up of a group of secreted proteins that share sequence similarity. Members of this family are found in animal s, plants, and fungi, and their shared sequence similarity suggests th at members share a common, but as yet unknown, molecular function. As a first step in defining the function of CAP family proteins, an 878 b p partial cDNA encoding a novel member of the CAP family was cloned by the polymerase chain reaction (PCR) from total RNA of adult Drosophil a. The cDNA contained the complete coding sequence for a protein 256 a mino acids in length, as well as the complete 3' untranslated region ( UTR) and a portion of the 5' UTR. The protein, named Antigen 5-related (Agr), was most similar in sequence to antigen 5 (Ag5), a CAP family member found in social wasps and ants. The corresponding Agr RNA is ab out 1 kb in length and is present at all stages of development, with h ighest levels observed in adults. Agr RNA is transcribed from a single gene that is located within region 12F of the X chromosome. The ident ification of Agr in Drosophila expands the number of known CAP family members to well over four dozen. Further studies of Agr and the gene w hich encodes this protein using the Drosophila model system may help p rovide important insight into the molecular functioning of this little known, but increasingly significant protein family. (C) 1997 Elsevier Science B.V.