RESUMO
We have identified the first putative integral membrane pentraxin and named it neuronal pentraxin receptor (NPR). NPR is enriched by affinity chromatography on columns of a snake venom toxin, taipoxin, and columns of the taipoxin-binding proteins neuronal pentraxin 1 (NP1), neuronal pentraxin 2 (NP2), and taipoxin-associated calcium-binding protein 49 (TCBP49). The predominant form of NPR contains an putative NH2-terminal transmembrane domain and all forms of NPR are glycosylated. NPR has 49 and 48% amino acid identity to NP1 and NP2, respectively, and NPR message is expressed in neuronal regions that express NP1 and NP2. We suggest that NPR, NP1, NP2, and TCBP49 are involved in a pathway responsible for the transport of taipoxin into synapses and that this may represent a novel neuronal uptake pathway involved in the clearance of synaptic debris.
Assuntos
Proteína C-Reativa/química , Proteína C-Reativa/metabolismo , Proteínas de Ligação ao Cálcio/metabolismo , Venenos Elapídicos/metabolismo , Glicoproteínas de Membrana/isolamento & purificação , Proteínas do Tecido Nervoso/química , Proteínas do Tecido Nervoso/metabolismo , Receptores de Superfície Celular/isolamento & purificação , Sequência de Aminoácidos , Animais , Sequência de Bases , Cromatografia de Afinidade , Hibridização In Situ , Manosil-Glicoproteína Endo-beta-N-Acetilglucosaminidase/metabolismo , Glicoproteínas de Membrana/genética , Glicoproteínas de Membrana/metabolismo , Dados de Sequência Molecular , Peso Molecular , RNA Mensageiro/metabolismo , Ratos , Receptores de Superfície Celular/genética , Receptores de Superfície Celular/metabolismo , Alinhamento de SequênciaRESUMO
We have previously identified novel members of the pentraxin family (neuronal pentraxin 1 and 2) that are expressed in the nervous system. Neuronal pentraxin 1 (NP1) was identified as a rat protein that may mediate the uptake of synaptic material and the presynaptic snake venom toxin, taipoxin. NP2 was identified as a separate gene discovered by screening for a human homolog for NP1. Here, we report human cDNA and mouse genomic DNA sequences for NP1 (gene symbol NPTX1). Human NP1 and mouse NP1 show 95 and 99% amino acid identity, respectively, with rat NP1 and conserve all potential glycosylation sites. Like rat NP1, human NP1 message is large (6.5 kb) and is exclusively localized to the nervous system. The mouse NP1 gene is 13 kb in length and contains four introns that break the coding sequence of NP1 in the same positions as the introns of the human NP2 gene. The human and mouse NP1 genes are localized to chromosome 17q25.1-q25.2 and chromosome 11e2-e1.3, respectively. These data demonstrate the existence of a separate family of pentraxin proteins that are expressed in the human brain and other tissues and that may play important roles in the uptake of extracellular material.
