Reticulon (RTN) family proteins are localized in the endoplasmic reticulum (ER). At least four different RTN genes have been identified in mammals. but in most cases. the functions of the encoded proteins except mammalian RTN4-A and RTN4-B are unknown. Each RTN gene produces 1-3 proteins by different promoters and alternative splicing. In Caenorhabditis elegans, there is a single gene (rtn gene) encoding three reticulon proteins, nRTN-A, B, and C. mRNA of nRTN-C is expressed in germ cells and embryos. However. nRTN-C protein is only expressed during embryogenesis and rapidly disappears after hatch. By yeast two-hybrid screening. two clones encoding the same C-terminal region of RME-1, a protein functioning in the endocytic recycling, were isolated. These findings suggest that nRTN-C functions in the endocytic pathway during embryogenesis. (C) 2002 Elsevier Science (USA). All rights reserved.