The nucleotide sequence of molecular clones of DNA from a retrovirus, ARV-2, associated with the acquired immune deficiency syndrome (AIDS) was determined. Proviral DNA of ARV-2 (9737 base pairs) has long terminal repeat structures (636 base pairs) and long open reading frames encoding gag (506 codons), pol (1003 codons), and env (863 codons) genes. Two additional open reading frames were identified. Significant amino acid homology with several other retroviruses was noted in the predicted product of gag and pol, but ARV-2 was as closely related to murine and avian retroviruses as it was to human T-cell leukemia viruses (HTLV-I and HTLV-II). By means of an SV-40 vector in transfected simian cells, the cloned gag and env genes of ARV-2 were shown to express viral proteins.
Genomic DNA libraries were constructed for Chlamydia trachomatis serovars B and C by using BamHI fragments, and recombinants that contained the major outer membrane protein (ompl) gene for each serovar were identified and sequenced. Comparisons between these gene sequences and the gene from serovar L2 demonstrated fewer base pair differences between serovars L2 and B than between L2 and C; this finding is consistent with the serologic and antigenic relationships among these serovars. The translated amino acid sequence for the major outer membrane proteins (MOMPs) contained the same number of amino acids for serovars L2 and B, whereas the serovar C MOMP contained three additional amino acids. The antigenic diversity of the chlamydial MOMP was reflected in four sequence-variable domains, and two of these domains were candidates for the putative type-specific antigenic determinant. The molecular basis of ompl gene diversity among C. trachomatis serovars was observed to be clustered nucleotide substitutions for closely related serovars and insertions or deletions for distantly related serovars.Chlamydia trachomatis is a procaryote that is the cause of a wide spectrum of human diseases affecting hundreds of millions of people worldwide. The most notable diseases are trachoma, a blinding eye disease, and genitourinary tract diseases that often result in sterility (7). Chlamydiae are obligate intracellular bacteria that have a unique biphasic growth cycle which facilitates their survival in two discontinuous habitats. The major outer membrane protein (MOMP) of chlamydiae is one of the principal cell wall surface components that is responsible for the structural integrity of the extracellular infectious elementary body and the developmental conversion to the plastic and fragile intracellular reticulate body (8). This protein also has poreforming capabilities that permit exchange of nutrients for the reticulate body form (2). The structural and porin functions of the MOMP are mediated by disulfide bond interactions within and between MOMP molecules and other components (16).Surface components of chlamydiae are presumed to modulate the essential biological events of attachment, induced phagocytosis, inhibition of phagolysosomal fusion, infectivity, toxicity, and the host immune responses that contribute to immunity and pathogenesis (21). The immunodominant MOMP has been implicated in some of these important functions, primarily by association of many of these processes with a type-specific antigen. The predominant typespecific determinant for chlamydiae has been attributed to the MOMP by using monospecific (4) and monoclonal (25, 27) antibodies.C. trachomatis has been extensively characterized serologically, with more than 15 serovars defined by polyvalent antisera (28) and monoclonal antibodies (29). Monoclonal antibody specificities to MOMP define species-, subspecies-, and type-specific determinants; thus, the MOMP represents a serological matrix of epitopes such that a single molecule possesses both constant and varia...
The structure of the messenger RNA (mRNA) encoding the precursor to mouse submaxillary epidermal growth factor (EGF) was determined from the sequence of a set of overlapping complementary DNA's (cDNA). The mRNA is unexpectedly large, about 4750 nucleotide bases, and predicts the sequence of preproEGF, a protein of 1217 amino acids (133,000 molecular weight). The EGF moiety (53 amino acids) is flanked by polypeptide segments of 976 and 188 amino acids at its amino and carboyxl termini, respectively. The amino terminal segment of the precursor contains seven peptides with sequences that are similar but not identical to EGF.
Complementary DNA clones encoding the human kidney epidermal growth factor (EGF) precursor have been isolated and sequenced. They predict the sequence of a 1,207 amino acid protein which contains EGF flanked by polypeptide segments of 970 and 184 residues at its NH2- and COOH-termini, respectively. The structural organization of the human EGF precursor is similar to that previously described for the mouse protein and there is 66% identity between the two sequences. Transfection of COS-7 cells with the human EGF precursor cDNA linked to the SV40 early promoter indicate that it can be synthesized as a membrane protein with its NH2-terminus external to the cell surface. The human EGF precursor gene is approximately 110 kilobase pairs and has 24 exons. Its exon-intron organization revealed that various domains of the EGF precursor are encoded by individual exons. Moreover, 15 of the 24 exons encode protein segments that are homologous to sequences in other proteins. Exon duplication and shuffling appear to have played an important role in determining the present structure of this protein.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.