Mannose-binding lectin

MBL2
Available structures PDB Ortholog search: PDBe RCSB List of PDB id codes 1HUP
Identifiers
Aliases	MBL2, COLEC1, HSMBPC, MBL, MBL2D, MBP, MBP-C, MBP1, MBPD, mannose binding lectin 2
External IDs	OMIM: 154545 MGI: 96924 HomoloGene: 110436 GeneCards: MBL2
Gene ontology Molecular function • calcium ion binding • calcium-dependent protein binding • protein binding • mannose binding • receptor binding • carbohydrate binding • serine-type endopeptidase activity Cellular component • collagen trimer • extracellular region • cell surface • extracellular space Biological process • complement activation, lectin pathway • positive regulation of phagocytosis • killing by host of symbiont cells • negative regulation of growth of symbiont in host • negative regulation of viral process • immune system process • complement activation • response to oxidative stress • acute-phase response • defense response to bacterium • complement activation, classical pathway • opsonization • defense response to Gram-positive bacterium • innate immune response • proteolysis Sources:Amigo / QuickGO
RNA expression pattern
More reference expression data
Orthologs
Species	Human	Mouse
Entrez	4153	17195
Ensembl	ENSG00000165471	ENSMUSG00000024863
UniProt	P11226	P41317
RefSeq (mRNA)	NM_000242	NM_010776
RefSeq (protein)	NP_000233	NP_034906
Location (UCSC)	Chr 10: 52.77 – 52.77 Mb	Chr 19: 30.23 – 30.24 Mb
PubMed search

1HUP

4153

17195

ENSG00000165471

ENSMUSG00000024863

P11226

P41317

NM_000242

NM_010776

NP_000233

NP_034906

Mannose-binding lectin (MBL), also called mannose-binding protein or mannan-binding protein (MBP), is a lectin that is instrumental in innate immunity via the lectin pathway.

MBL has an oligomeric structure (400-700 kDa), built of subunits that contain three presumably identical peptide chains of about 30 kDa each.

Although MBL can form several oligomeric forms, there are indications that dimers and trimers are not biologically active and at least a tetramer form is needed for activation of complement.

Human MBL2 gene is located on chromosome 10q11.2-q21. Mice have two homologous genes, but in human the first of them was lost. A low level expression of an MBL1 pseudogene 1 (MBL1P1) was detected in liver. The pseudogene encodes a truncated 51-amino acid protein that is homologous to the MBLA isoform in rodents and some primates.

Structural mutations in exon 1 of the human MBL2 gene, at codon 52 (Arg to Cys, allele D), codon 54 (Gly to Asp, allele B) and codon 57 (Gly to Glu, allele C), also independently reduce the level of functional serum MBL by disrupting the collagenous structure of the protein. Furthermore, several nucleotide substitutions in the promoter region of the MBL2 gene at position −550 (H/L polymorphism), −221 (X/Y polymorphism) and −427, −349, −336, del (−324 to −329), −70 and +4 (P/Q polymorphisms) affect the MBL serum concentration. Both the frequency of structural mutations and the promoter polymorphisms that are in strong linkage disequilibrium vary among ethnic groups resulting in seven major haplotypes: HYPA, LYQA, LYPA, LXPA, LYPB, LYQC and HYPD. Differences in the distribution of these haplotypes are the major cause of interracial variations in MBL serum levels. Both HYPA and LYQA are high-producing haplotypes, LYPA intermediate-producing haplotype and LXPA low-producing haplotype, whereas LYPB, LYQC and HYPD are defective haplotypes, which cause a severe MBL deficiency.

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