Protein: Lysosomal cobalamin transport escort protein LMBD1 (LMBD1) (HDAg-L-interacting protein NESI) (LMBR1 domain-containing protein 1) (Nuclear export signal-interacting protein) (Q9NUN5)
Organism: Homo sapiens (Human)
Function: Lysosomal membrane chaperone required to export cobalamin (vitamin B12) from the lysosome to the cytosol, allowing its conversion to cofactors. Targets ABCD4 transporter from the endoplasmic reticulum to the lysosome. Then forms a complex with lysosomal ABCD4 and cytoplasmic MMACHC to transport cobalamin across the lysosomal membrane. Acts as an adapter protein which plays an important role in mediating and regulating the internalization of the insulin receptor (INSR) (By similarity). Involved in clathrin-mediated endocytosis of INSR via its interaction with adapter protein complex 2 (By similarity). Essential for the initiation of gastrulation and early formation of mesoderm structures during embryogenesis (By similarity).
Subcellular location: Endoplasmic reticulum membrane {ECO:0000269|PubMed:27456980}. Lysosome membrane {ECO:0000269|PubMed:19136951, ECO:0000269|PubMed:27456980, ECO:0000269|PubMed:28572511, ECO:0000269|PubMed:33845046}; Multi-pass membrane protein {ECO:0000255}. Cell membrane {ECO:0000250|UniProtKB:Q8K0B2}; Multi-pass membrane protein {ECO:0000255}. Cytoplasmic vesicle, clathrin-coated vesicle {ECO:0000250|UniProtKB:Q8K0B2}.
Sequence: MATSGAASAELVIGWCIFGLLLLAILAFCWIYVRKYQSRRESEVVSTITAIFSLAIALITSALLPVDIFLVSYMKNQNGTFKDWANANVSRQIEDTVLYGYYTLYSVILFCVFFWIPFVYFYYEEKDDDDTSKCTQIKTALKYTLGFVVICALLLLVGAFVPLNVPNNKNSTEWEKVKSLFEELGSSHGLAALSFSISSLTLIGMLAAITYTAYGMSALPLNLIKGTRSAAYERLENTEDIEEVEQHIQTIKSKSKDGRPLPARDKRALKQFEERLRTLKKRERHLEFIENSWWTKFCGALRPLKIVWGIFFILVALLFVISLFLSNLDKALHSAGIDSGFIIFGANLSNPLNMLLPLLQTVFPLDYILITIIIMYFIFTSMAGIRNIGIWFFWIRLYKIRRGRTRPQALLFLCMILLLIVLHTSYMIYSLAPQYVMYGSQNYLIETNITSDNHKGNSTLSVPKRCDADAPEDQCTVTRTYLFLHKFWFFSAAYYFGNWAFLGVFLIGLIVSCCKGKKSVIEGVDEDSDISDDEPSVYSA
InterPro domains: - IPR050854: Lysosomal Cobalamin Transport Escort Protein LMBD1 (family) [7-536]
- IPR006876: LMBR1-like membrane protein (family) [17-287]
Interaction partners: - Lysosomal cobalamin transporter ABCD4
- Cobalamin trafficking protein CblD
- Methylmalonic aciduria type A protein, mitochondrial
- Cyanocobalamin reductase / alkylcobalamin dealkylase
- Corrinoid adenosyltransferase MMAB
- Methionine synthase
- Methionine synthase reductase
- Methylmalonyl-CoA mutase, mitochondrial
- CD320 antigen
- Transcobalamin-2
Gene Ontology annotations:
Molecular Function (MF): GO:0003674 (molecular function), GO:0005488 (binding), GO:0044877 (protein-containing complex binding), GO:0005515 (protein binding), GO:0030276 (clathrin binding), GO:0005102 (signaling receptor binding), GO:0005158 (insulin receptor binding)
Biological Process (BP): GO:0008150 (biological process), GO:0051179 (localization), GO:0051234 (establishment of localization), GO:0006810 (transport), GO:0016192 (vesicle-mediated transport), GO:0006897 (endocytosis), GO:0006898 (receptor-mediated endocytosis), GO:0072583 (clathrin-dependent endocytosis)
Cellular Component (CC): GO:0005575 (cellular component), GO:0110165 (cellular anatomical entity), GO:0005622 (intracellular anatomical structure), GO:0043226 (organelle), GO:0043229 (intracellular organelle), GO:0043227 (membrane-bounded organelle), GO:0043231 (intracellular membrane-bounded organelle)