title: Molecular characterization of a transport vesicle protein Neurensin-2, a homologue of Neurensin-1, expressed in neural cells.
abstract: We have isolated and characterized a novel cDNA encoding a small neuronal membrane protein showing high sequence homology to Neuro-p24/Neurensin-1, a protein containing a microtubule-associated domain at the carboxyl-terminus and exclusively localized to small vesicles of neurons. The newly identified Neurensin-2 constitutes two-membrane spanning domains but not the microtubule-binding domain, with a molecular mass of 28 kDa. Neurensin-2 mRNA is expressed only in brain, whereas the protein expressed in various neurons including those of the thalamus/hypothalamus and hippocampus, of postnatally developing mice. While the levels of Neurensin-1 mRNA and protein in retinoic acid-exposed mouse neuroblastoma Neuro2a cells increased, those of Neurensin-2 mRNA and protein remained unchanged. When the Neurensin-2 cDNA was transfected into Neuro2a cells, Neurensin-2 was expressed in small vesicles including lysosomes in the perinuclear region. On the cotransfection of Neurensin-1 and -2 cDNA into Neuro2a cells, Neurensin-2 was mainly found in small vesicles of the cell body and Neurensin-1 in those of growth cones. In nerve growth factor-stimulated PC12 cells, the intracellular localization of these proteins also differed. Furthermore, immunochemical staining of mouse brain revealed that Neurensin-1 and -2 had a similar distribution in many regions such as the Diagonal band, hippocampus, amygdaloid nucleus, and habenula nucleus, but differed in the intracellular localization as follows: Neurensin-1 was found mainly in neuritic processes, while Neurensin-2 was found in cell bodies. Thus, both Neurensin-1, and -2 are localized in small vesicles in neural cells, but their localizations of the vesicles are not always the same by each other, suggesting that they are under separate regulation.
authors.affiliation: Department of Biotechnology, Kyoto Institute of Technology, Kyoto 606-8585, Japan.
authors.forename: Katsuyuki
authors.initials: K
authors.lastname: Nakanishi
authors.forename: Mizuho
authors.initials: M
authors.lastname: Ida
authors.forename: Haruno
authors.initials: H
authors.lastname: Suzuki
authors.forename: Chiaki
authors.initials: C
authors.lastname: Kitano
authors.forename: Akitsugu
authors.initials: A
authors.lastname: Yamamoto
authors.forename: Nozomu
authors.initials: N
authors.lastname: Mori
authors.forename: Masasuke
authors.initials: M
authors.lastname: Araki
authors.forename: Shigeru
authors.initials: S
authors.lastname: Taketani
mesh_terms: D000818:Animals; D015152:Blotting, Northern / Q000379:methods; D015153:Blotting, Western / Q000379:methods; D001921:Brain / Q000166:cytology / Q000378:metabolism; D002460:Cell Line; D002522:Chlorocebus aethiops; D003001:Cloning, Molecular / Q000379:methods; D053938:DNA Fragmentation / Q000502:physiology; D015870:Gene Expression / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D051379:Mice; D020932:Nerve Growth Factor / Q000494:pharmacology; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D016415:Sequence Alignment / Q000379:methods; D017386:Sequence Homology, Amino Acid; D014162:Transfection / Q000379:methods; D033921:Vesicular Transport Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D009419:Nerve Tissue Proteins; C481124:Neuro-p24 protein, mouse; D033921:Vesicular Transport Proteins; D020932:Nerve Growth Factor