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Abstract: H2-M1 is a non-classical major histocompatibility complex (MHC) class I gene that is highly divergent from classical class I genes:M1 was the first gene in the recently classifiedM region of the mouseMHC to be cloned. Although theM1 DNA sequence contains normal splice sites, open reading frames within its exons, and a recognizable promoter, noM1 transcripts were detected in various healthy mouse tissues. However,M1 transcripts were detected in transfected L cells and in vivo in brains ofM1 transgenic mice, albeit at very low levels, and the level of expression is correlated with transgene copy number. Analysis of theM1 promoter region identified a competent promoter capable of directing transcription, but whose expression is repressed by two strong upstream silencer elements, one mapping between −184 base pairs (bp) and −266 bp and the other between −1149 bp and −1702 bp. These studies suggest thatM1 expression is highly regulated and restricted either temporally or to a very limited number of cell types.

Abstract:  Using cDNA hybridization selection techniques, we identified seven new genes in a 280 kilobase YAC covering the HLA-F locus. The new genes were mapped back to the YAC by a combination of optical restriction mapping and pulse field gel electrophoresis. Northern analysis of individual clones demonstrated the presence of either different mRNA sizes or different expression patterns. Two of the cDNA clones were expressed only in lymphoid cell lines: one in Jurkat cells (T cell) and another in JY cells (B cell). All the genes lacked sequence similarity to any known classical and non-classical major histocompatibility complex (MHC) class I genes, indicating that the MHC class I region has more functions than anticipated. Of the seven new genes, one is highly similar (97%) to mouse 60S ribosomal protein, and another is homologous to diubiquitin proteins. Of the two G-coupled receptor-like cDNAs, one was fully sequenced and found to be an olfactory receptor-like gene. The study strengthens evidence that the MHC complex not only plays a key role in the immune system, but also contributes to non-immunological functions.

Abstract:  Two genes belonging to the heat shock protein 70 gene family have been cloned from the colonial protochordate Botryllus schlosseri. The two intronless genes (HSP70.1 and HSP70.2) exhibit 93.6% sequence identity within the predicted coding region, and 83.3% and 81.7% sequence identity in the 5′ and 3′ flanking regions, respectively. The predicted amino acid sequences are 95% identical and contain several signatures characteristic of cytoplasmic eukaryotic HSP70 genes (Gupta et al. 1994; Rensing and Maier 1994). Northern blotting and sequence analysis suggest that both genes are heat-inducible members of the HSP70 gene family. Given these characteristics, HSP70.1 and HSP70.2 appear to be good candidates for protochordate homologues of the major histocompatibility complex-linked HSP70 genes of human, mouse, and rat (Milner and Campbell 1990; Walter et al. 1994). Further experiments to determine whether there is functional evidence for such similarity are in progress.

Using cDNA hybridization selection techniques, we identified seven new genes in a 280 kilobase YAC coveting theHLA-Flocus. The new genes were mapped back to the YAC by a combination of optical restriction mapping and pulse field gel electrophoresis. Northern analysis of individual clones demonstrated the presence of either different mRNA sizes or different expression patterns. Two of the cDNA clones were expressed only in lymphoid cell lines: one in Jurkat cells (T cell) and another in JY cells (B cell). All the genes lacked sequence similarity to any known classical and non-classical major histocompatibility complex (MHC) class I genes, indicating that theMHCclass I region has more functions than anticipated. Of the seven new genes, one is highly similar (97%) to mouse 60S ribosomal protein, and another is homologous to diubiquitin proteins. Of the two G-coupled receptor-like cDNAs, one was fully sequenced and found to be an olfactory receptor-like gene. The study strengthens evidence that theMHCcomplex not only plays a key role in the immune system, but also contributes to non-immunological functions.

Two genes belonging to the heat shock protein 70 gene family have been cloned from the colonial protochordateBotryllus schlosseri.The two intronless genes(HSP70.1andHSP70.2)exhibit 93.6% sequence identity within the predicted coding region, and 83.3% and 81.7% sequence identity in the 5′ and 3′ flanking regions, respectively. The predicted amino acid sequences are 95% identical and contain several signatures characteristic of cytoplasmic eukaryoticHSP70genes (Gupta et al. 1994; Rensing and Maier 1994). Northern blotting and sequence analysis suggest that both genes are heat-inducible merebees of theHSP70gene family. Given these characteristics,HSP70.1andHSP70.2appear to be good candidates for protochordate homologues of the major histocompatibility complex-linkedHSP70genes of human, mouse, and rat (Milner and Campbell 1990; Walter et al. 1994). Further experiments to determine whether there is functional evidence for such similarity are in progress.