RESUMO
TAPL is a half-type ABC transporter with sequence similarity to TAP1 and TAP2 that is transcribed in various rat tissues [Yamaguchi, Y., Kasano, M., Terada, T., Sato, R., and Maeda, M. (1999) FEBS Lett. 457, 231-236]. Primary structures of the human and mouse orthologous counterparts were deduced from cDNAs cloned by means of polymerase chain reaction, and they were compared with that of the rat. The mammalian TAPLs (rat, mouse, and human) are highly conserved, since about 95% of the amino acid residues are identical between rodents and man. Phylogenetic analysis demonstrated that the evolutional rate of TAPL is much slower than those of TAP1 and TAP2, although TAPL could have diverged from an ancestor of TAP1 or that of TAP1 and TAP2. The TAPL-GFP fusion protein transiently expressed in Cos-1 cells was co-localized with PDI, suggesting that TAPL is inserted into endoplasmic reticulum membrane. The conservation of the peptide-binding motifs of TAP proteins in TAPL raises the possibility that the TAPL might be a peptide transporter. The gene for human TAPL is assigned to chromosome 12q24.31-q24.32, while those for TAP1 and TAP2 are located at the MHC locus of chromosome 6p21.!3. Furthermore, the transcription of TAPL gene is not responsive to interferon-gamma, in contrast to TAP1 and TAP2. These results indicate that the gene regulation of TAPL is different from those of TAP1 and TAP2.
Assuntos
Transportadores de Cassetes de Ligação de ATP/genética , Sequência Conservada/genética , Regulação da Expressão Gênica/efeitos dos fármacos , Interferon gama/farmacologia , Membro 2 da Subfamília B de Transportadores de Cassetes de Ligação de ATP , Membro 3 da Subfamília B de Transportadores de Cassetes de Ligação de ATP , Transportadores de Cassetes de Ligação de ATP/química , Transportadores de Cassetes de Ligação de ATP/metabolismo , Sequência de Aminoácidos , Animais , Sítios de Ligação , Células COS , Linhagem Celular , Membrana Celular/química , Cromossomos Humanos Par 12/genética , Clonagem Molecular , Citoplasma/química , Humanos , Hibridização in Situ Fluorescente , Dados de Sequência Molecular , Filogenia , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Ratos , Proteínas Recombinantes de Fusão , Alinhamento de Sequência , Homologia de Sequência de AminoácidosRESUMO
Polymerase chain reaction amplification of cDNA from rat intestine revealed the expression of a novel ABC transporter, TAPL (TAP-like). Subsequently, the protein sequence was deduced from the nucleotide sequence of cDNA carrying the entire coding region. TAPL is transcribed ubiquitously in various rat tissues. The protein, with 762 amino acid residues, has potential transmembrane domains, and an ATP-binding domain in its amino and carboxyl terminal regions, respectively, and is highly homologous to TAP1 and TAP2 (transporters associated with antigen presentation/processing): pairwise comparisons with TAPL demonstrated 39 and 41% of the residues are identical, respectively. These numerical values are essentially the same as that for TAP1 and TAP2 (39%), and the hydropathy profiles of TAPL, TAP1 and TAP2 are quite similar. The similarity among these three proteins suggests that they could be derived from a common ancestral gene. Furthermore, we found that there is a potential splicing isoform, sharing the amino terminal 720 amino acid residues of TAPL.
Assuntos
Transportadores de Cassetes de Ligação de ATP/química , Transportadores de Cassetes de Ligação de ATP/genética , Membro 2 da Subfamília B de Transportadores de Cassetes de Ligação de ATP , Membro 3 da Subfamília B de Transportadores de Cassetes de Ligação de ATP , Transportadores de Cassetes de Ligação de ATP/metabolismo , Sequência de Aminoácidos , Animais , Sequência de Bases , Transporte Biológico , Clonagem Molecular , Citoplasma/metabolismo , DNA Complementar/análise , Retículo Endoplasmático/metabolismo , Antígenos de Histocompatibilidade Classe I/imunologia , Antígenos de Histocompatibilidade Classe I/metabolismo , Mucosa Intestinal/metabolismo , Dados de Sequência Molecular , Peptídeos/metabolismo , RNA Mensageiro/metabolismo , Ratos , Ratos Sprague-Dawley , Homologia de Sequência de Aminoácidos , Homologia de Sequência do Ácido Nucleico , Distribuição TecidualRESUMO
Basal PC secretion in the type II pneumocytes from bronchitic rats was the same as that in the type II pneumocytes from normal rats. Neutrophils activated by opsonized zymosan or PMA, stimulated PC secretion in type II pneumocytes without causing any cell damage. The stimulation required close accession or attachment of neutrophils and type II pneumocytes and was not affected by the pretreatment with either SOD, catalase, AA861 or alpha 1-antitrypsin.
