Myelin/oligodendrocyte glycoprotein (MOG) is a primary target autoantigen in experimental autoimmune encephalomyelitis, a widely used animal model for autoimmune demyelinating diseases such as multiple sclerosis. We have isolated several rat MOG cDNAs and confirmed their identity by comparison with MOG N-terminal peptide sequence. As expected, MOG mRNA expression is CNS-specific and peaks during active myelination. Our studies show that full length MOG mRNA is approximately 1.6 kb and encodes a signal peptide of 27 amino acids, followed by 218 residues for mature MOG (24,962 MW). A single site for N-glycosylation is found at Asn-31. Rather than the ubiquitous AAUAAA polyadenylation signal, a series of three overlapping, rare poly A signals were identified. The N-terminal half of mature MOG shares 52% identity with bovine butyrophilin, a possible lipid receptor. This same region has 39% identity with chicken B-G antigen, a major histocompatibility complex antigen involved in B cell selection and immune repertoire development. We show that both MOG and butyrophilin, each exhibiting a single Ig-like variable region domain, meet criteria for inclusion in the immunoglobulin superfamily. Moreover, MOG appears to represent a unique member of this superfamily in that it possesses two potential transmembrane domains, in contrast to a single membrane-spanning domain or glycophospholipid anchor found in all other members of Ig superfamily members.

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This study addressed the possibility that proto-myb (also called c-myb), the cellular homolog of a retroviral transforming gene, plays a role in hemopoiesis, particularly during maturation of T cells. By gel blot hybridization, we confirmed previous reports that proto-myb transcripts are found at much higher levels in thymic lymphocytes and cells of the erythroid lineage than in other tissue sources. Using dot blot hybridizations, we demonstrated further that similar levels of proto-myb expression are found in thymic lymphocytes taken from young mice with active thymuses and from old mice whose thymuses have undergone involution and that the extent of proto-myb expression decreases at least 10-fold as T cells progress from immature cortical thymocytes to the mature, resting T cells taken from lymph nodes. These results suggest that the protein product of proto-myb functions during T-cell differentiation.

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The gene for the mouse myelin proteolipid protein has been isolated and the seven exons have been sequenced. Since the sequence of a rat proteolipid protein cDNA and partial sequence of the human proteolipid protein gene have been determined, it was possible to demonstrate a very high degree of conservation for the protelipid protein gene exons among species. While there are some nucleotide changes, the protein coding region of the mouse gene encodes protein that is totally conserved relative to both rat and human prteolipid proteins. The regulatory and noncoding regions of the proteolipid protein gene are also highly conserved. The upstream regulatory and 5′‐noncoding region of the gene is 92% homologous to the comparable region of the human proteolipid protein gene, and the 3′‐noncoding region of the mouse gene is approximately 90% homologous to a rat proteolipid protein cDNA through 2,200 nucleotides of 3′‐noncoding DNA.S1 nuclease protection experiments indicated that the major 5′‐end for proteolipid protein mRNAs from mouse, rat human, ro baboon is approximately 147–160 nucleotides upstream from the initial methionine codon of the protein coding region. Other S1 nuclease protection experiments indicated the possible existence of an alernative splice site within exon 3, which may produce mRNA for DM20. This mRNA is approximately 100 nucleotides shorter than that for the protelipid protein, and it is missing the latter half of exon 3, that is, amino acids 116–150 of the proteolipid protein sequence.