Lipocalin 1

Lipocalin-1 is a protein that in humans is encoded by the LCN1 gene.^[3][4]

LCN1
Available structures PDB Human UniProt search: PDBe RCSB List of PDB id codes 1XKI, 3EYC, 4QAF
Identifiers
Aliases	LCN1, PMFA, TLC, TP, VEGP, lipocalin 1
External IDs	OMIM: 151675; HomoloGene: 48099; GeneCards: LCN1; OMA:LCN1 - orthologs
Gene location (Human) Chr. Chromosome 9 (human)[1] Band 9q34.3 Start 135,521,438 bp[1] End 135,526,540 bp[1]
RNA expression pattern Bgee Human Mouse (ortholog) Top expressed in lacrimal gland testicle tongue body of tongue superior surface of tongue olfactory zone of nasal mucosa right uterine tube anterior pituitary hippocampus proper oral cavity n/a More reference expression data BioGPS n/a
Gene ontology Molecular function cysteine-type endopeptidase inhibitor activity zinc ion binding chloride ion binding signaling receptor binding small molecule binding Cellular component extracellular region extracellular exosome extracellular space Biological process retina homeostasis sensory perception of taste response to stimulus proteolysis long-chain fatty acid transport negative regulation of endopeptidase activity transport Sources:Amigo / QuickGO
Orthologs Species Human Mouse Entrez 3933 n/a Ensembl ENSG00000160349 n/a UniProt P31025 n/a RefSeq (mRNA) NM_001252617 NM_001252618 NM_001252619 NM_002297 n/a RefSeq (protein) NP_001239546 NP_001239547 NP_001239548 NP_002288 NP_001239546.1 NP_002288.1 n/a Location (UCSC) Chr 9: 135.52 – 135.53 Mb n/a PubMed search [2] n/a
Wikidata
View/Edit Human

The protein encoded by this gene belongs to the lipocalin family. Lipocalins are a group of extracellular proteins that are able to bind lipophiles by enclosure within their structures to minimize solvent contact. This protein may bind hydrophobic ligands and inhibit cysteine proteinases. It may also play a role in taste reception.^[4]

Structure

NMR Structure of LCN1

Proteins are classified into the lipocalin family by their 8 antiparallel beta-sheets that form a barrel structure which acts as the binding site for ligands.

Function

Lipocalin-1 (LCN1) is capable of binding a wide variety of lipophilic molecules along with zinc and chloride ions. Because of this feature, LCN1’s main function is thought to be the removal of potentially harmful lipids and lipophilic molecules from the body by binding them. The LCN1-Ligand complex is then imported via Lipocalin-1-Interacting Membrane Receptor (LIMR) so the bound molecule can be broken down safely within the cell.^[5] This process of retrieving molecules may impact several processes including pheromone signaling, immunodulation, inflammation, detoxification, tissue development, apoptosis and more.

LCN1 shares three sequence motifs with cystatins which enables LCN1 to act in a similar manner to cystatins as a cysteine proteinase inhibitor. These domains have specifically been shown to bind Papain.^[6][7]

LCN1 also plays a role in stabilizing the lipid layer of the tear film, though the details of this are not yet well understood.^[8][9]

History

Lipocalin-1 was initially thought to be produced exclusively by exocrine glands but has also been found in corticotrophs of the pituitary gland.^[10]

Alternate Names: Human Tear Prealbumin, Tear Lipocalin, von Ebner’s Gland Protein

Clinical

When a cell is under stress, due to inflammation, infection, or otherwise, it will produce elevated levels of lipocalin-1 (LCN1). This makes it a potential noninvasive biomarker for various diseases. This potential has been shown in a study of IVF blastocysts, where elevated levels of LCN1 indicated aneuploidy in the blastocyst.^[11]