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From a Xenopus tailbud cDNA library, we obtained the cDNA for a novel cadherin which was named as XmN-cadherin (Xenopus maternally expressed neural cadherin). The cDNA consisted of 3690 bp and encoded 922 amino acid residues. XmN-cadherin preserved five extracellular cadherin motifs, a single transmembrane domain, and a cytoplasmic domain, and was closely related by its sequence to R- and N-cadherin. In the adult frog, XmN-cadherin mRNA was detected strongly in ovary, testis, brain, eye, and kidney, and weakly in stomach, and intestine. In the egg, the mRNA occurred as a maternal mRNA at a relatively high level, and its level became very low by the neurula stage, then increased steadily thereafter. Dissection experiments with 8-cell stage and neurula stage embryos revealed that the maternally inherited mRNA was relatively uniformly distributed within the embryo. By a sharp contrast, whole mount in situ hybridization revealed that the zygotically expressed mRNA occurred almost exclusively in neural tissues such as brain, the anterior part of spinal cord, and the optic and otic vesicles. Thus, XmN-cadherin appears to have at least triple functions; it probably contributes in early embryos to cell-type non-specific cell adhesion, but in post-neurula embryos may be responsible for the development and/or maintenance of anterior neural tissues, and may be used in adult frog for the development and/or maintenance of neural, endodermal and reproductive organs.

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SummaryThe transcription factor KBF2 has been characterized as a factor that binds to the NFkB site of mouse major histocompatibility complex (MHC) class I genes and its amino acid sequence has been shown to be identical to those of members of the recombination signalsequence binding protein (RBP-Jk) family. Previous studies by Amakawa et al. (Genomics 17, 306-315, 1993) demonstrated that the functional gene is localized at human chromosome 3q25. However, in the present study we showed by in situ hybridization With the functional KBF2/ RBPJk cosmid clone that the gene is localized at 9p12-13 and 9q13, namely, at the same loci as pseudogenes that were reported previously (Zhang et al., Jpn J Human Genet 39, 391-401, 1994). Key Words KBF2, RBP-Jk, cosmid, in situ hybridizationThe major histocompatibility complex (MHC) class I antigens specified by MHC class I genes play a key role in a number of immunological processes, particularly in the recognition of foreign antigens by cytotoxic T cells and natural killer ceils of the host (Zinkernagel and Doherty, 1979). In the mouse, the promoters of the K b and L d class I MHC genes have been used as models in studies of transcription (Israel et al., 1989). A factor designated KBF2, which can bind as a monomer to conserved sequence element (TGGGGATTCCCCA) located 165 bp upstream of the initiation site of the H-2K b class I gene. Interestingly, the same

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