Molecular Cloning of a Novel Human Collectin from Liver (CL-L1)

Abstract

Collectins are a C-lectin family with collagen-like sequences and carbohydrate recognition domains. These proteins can bind to carbohydrate antigens of microorganisms and inhibit their infection by direct neutralization and agglutination, the activation of complement through the lectin pathway, and opsonization by collectin receptors. Here we report the cloning of a cDNA encoding human collectin from liver (CL-L1 (collectin liver 1)) that has typical collectin structural characteristics, consisting of an N-terminal cysteine-rich domain, a collagen-like domain, a neck domain, and a carbohydrate recognition domain. The cDNA has an insert of 831 base pairs coding for a protein of 277 amino acid residues. The deduced amino acid sequence shows that this collectin has a unique repeat of four lysine residues in its C-terminal area. Northern blot, Western blot, and reverse transcription-polymerase chain reaction analyses showed that CL-L1 is present mainly in liver as a cytosolic protein and at low levels in placenta. More sensitive analyses by reverse transcription-polymerase chain reactions showed that most tissues (except skeletal muscle) have CL-L1 mRNA. Zoo-blot analysis indicated that CL-L1 is limited to mammals and birds. A chromosomal localization study indicated that the CL-L1 gene localizes to chromosome 8q23-q24.1, different from chromosome 10 of other human collectin genes. Expression studies of fusion proteins lacking the collagen and N-terminal domains produced in Escherichia coli affirmed that CL-L1 binds mannose weakly. CL-L1 and recombinant CL-L1 fusion proteins do not bind to mannan columns. Analysis of the phylogenetic tree of CL-L1 and other collectins indicated that CL-L1 belongs to a fourth subfamily of collectins following the mannan-binding protein, surfactant protein A, and surfactant protein D subfamilies including bovine conglutinin and collectin-43 (CL-43). These findings indicate that CL-L1 may be involved in different biological functions.

Transcriptional expression levels of chicken collectins are affected by avian influenza A virus inoculation

“…However, the chicken genome did not seem to contain a homologue for the second pulmonary collectin SP-D. In addition, chicken collectins 1, 2 and 3 were found which resemble the mammalian collectin liver 1 (CL-L1) (Ohtani et al, 1999), collectin kidney 1 (CL-K1) (Keshi et al, 2006) and collectin placenta 1 (CL-P1) (Ohtani et al, 2001). The biological roles of CL-L1 and CL-K1 have not been determined yet, leaving no indication for a possible role of chicken collectins cCL-1 and cCL-2.…”

A novel locus for syndromic chronic idiopathic intestinal pseudo-obstruction maps to chromosome 8q23–q24

“…(a member of the C-lectin family, which includes proteins that possess collagen-like sequences and carbohydrate recognition domains), 28 and SNTB1 (a dystrophin-associated protein). 29 Sequence analysis excluded all these genes as responsible for this new syndromic CIIP associated with Barrett esophagus.…”

The Membrane-type Collectin CL-P1 Is a Scavenger Receptor on Vascular Endothelial Cells

“…These lectins are found in vertebrates from avians to humans (2). There are four groups of collectins: the mannan-binding protein (MBP) group including MBP-A and MBP-C (3), the surfactant protein A (SP-A) group (4), the surfactant protein D (SP-D) group (5), and the newly isolated collectin liver 1 (CL-L1) (6). MBP can destroy bacteria through activation of the complement pathway (7) or opsonization via collectin receptors (8).…”