Identification and characterization of nCLP2, a novel C1q family protein expressed in the central nervous system.
The C1q family is characterized by the C-terminally conserved globular C1q (gC1q) domain. Although more than 30 C1q family proteins have been identified in mammals, many of them remain ill-defined with respect to their molecular and biological properties. Here, we report on a novel C1q family protein specifically expressed in the central nervous system (CNS), which we designated neural C1q-like protein (nCLP) 2. nCLP2 was secreted as disulphide-bonded multimers comprising trimeric units. The multimers were stabilized by interchain disulphide bonds involving the cysteine residues in the N-terminal variable region and the C-terminal gC1q domain. The expression of nCLP2 was restricted to several brain regions and retina, including regions associated with memory formation (i.e. hippocampus, entorhinal cortex, anterodorsal thalamic nucleus). Immunoelectron microscopy revealed that nCLP2 was localized in the mossy fibre axons of hippocampal granule cells and their synaptic boutons and clefts, implying that nCLP2 was anterogradely transported in mossy fibres and secreted from the presynaptic termini. These results suggest that nCLP2 plays roles in synaptic function and maintenance in the CNS.
Shimono
Chisei
C
Institute for Protein Research, Osaka University, Suita, Japan.
Manabe
Ri-Ichiroh
R
Yamada
Tomiko
T
Fukuda
Shiro
S
Kawai
Jun
J
Furutani
Yutaka
Y
Tsutsui
Ko
K
Ikenaka
Kazuhiro
K
Hayashizaki
Yoshihide
Y
Sekiguchi
Kiyotoshi
K
D000595:Amino Acid Sequence; D000818:Animals; D002490:Central Nervous System / Q000166:cytology / Q000378:metabolism*; D015922:Complement C1q / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D003545:Cysteine / Q000737:chemistry; D020869:Gene Expression Profiling; D015723:Gene Library; D051379:Mice; D008813:Mice, Inbred ICR; D008969:Molecular Sequence Data; D019599:Mossy Fibers, Hippocampal / Q000378:metabolism / Q000648:ultrastructure; D050505:Mutant Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D009928:Organ Specificity; D054730:Protein Interaction Domains and Motifs; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D055503:Protein Multimerization; D021382:Protein Sorting Signals; D021381:Protein Transport; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D012160:Retina / Q000166:cytology / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
D050505:Mutant Proteins; D009419:Nerve Tissue Proteins; D020033:Protein Isoforms; D021382:Protein Sorting Signals; D011993:Recombinant Fusion Proteins; C550804:neural C1q-like protein 2, mouse; D015922:Complement C1q; D003545:Cysteine