The TRIM family members contain a tripartite motif (TRIM), which includes RING, B-box, and coiled-coil domains, or collectively RBCC. They have been implicated in a variety of biological processes, such as the regulation of differentiation and development, and oncogenesis. In this study, we discovered a novel function of the TRIM family in early development. We report the expression of Trim36/Haprin during Xenopus laevis early embryogenesis and its involvement in somite formation. Temporal expression analysis indicated that Trim36/Haprin was present throughout embryogenesis. Spatial expression analysis showed that its expression was mainly confined to the nervous system and a portion of the posterior somite. Morpholino-mediated knockdown of Trim36/Haprin markedly and specifically inhibited the somite formation. We conclude that Trim36/Haprin plays all important role in the arrangement of somites during their formation. (C) 2008 Elsevier Inc. All rights reserved.