Lck

LCK
Available structures
PDB	Ortholog search: E9PI33 PDBe E9PI33 RCSB
List of PDB id codes
	1BHF, 1BHH, 1CWD, 1CWE, 1FBZ, 1H92, 1IJR, 1KIK, 1LCJ, 1LCK, 1LKK, 1LKL, 1Q68, 1Q69, 1QPC, 1QPD, 1QPE, 1QPJ, 1X27, 2IIM, 2OF2, 2OF4, 2OFU, 2OFV, 2OG8, 2PL0, 2ZM1, 2ZM4, 2ZYB, 3AC1, 3AC2, 3AC3, 3AC4, 3AC5, 3AC8, 3ACJ, 3ACK, 3AD4, 3AD5, 3AD6, 3B2W, 3BRH, 3BYM, 3BYO, 3BYS, 3BYU, 3KMM, 3KXZ, 3LCK, 3MPM, 4D8K, 4C3F
Identifiers
Aliases	LCK, LCK proto-oncogene, Src family tyrosine kinase, IMD22, LSK, YT16, p56lck, pp58lck
External IDs	OMIM: 153390 MGI: 96756 HomoloGene: 3911 GeneCards: LCK
Gene location (Human)
Chr.	Chromosome 1 (human)
End	32,286,165 bp
Gene location (Mouse)
Chr.	Chromosome 4 (mouse)
End	129,467,434 bp
RNA expression pattern
	Top expressed in
	thymus; ; lymph node; ; blood; ; appendix; ; spleen; ; superficial temporal artery; ; thymus; ; amniotic fluid; ; bone marrow; ; bone marrow cells;
	Top expressed in
	thymus; ; spleen; ; blood; ; otic placode; ; submandibular gland; ; subcutaneous adipose tissue; ; ankle joint; ; primitive streak; ; saccule; ; morula;
	More reference expression data
	; ;
	More reference expression data
Gene ontology
Molecular function	transferase activity; nucleotide binding; protein kinase activity; CD4 receptor binding; ATPase binding; SH2 domain binding; CD8 receptor binding; phosphatidylinositol 3-kinase binding; protein C-terminus binding; protein binding; identical protein binding; protein phosphatase binding; ATP binding; protein kinase binding; phosphatidylinositol-4,5-bisphosphate 3-kinase activity; kinase activity; protein serine/threonine phosphatase activity; non-membrane spanning protein tyrosine kinase activity; phosphotyrosine residue binding; protein tyrosine kinase activity; T cell receptor binding; signaling receptor binding;
Cellular component	cytoplasm; cytosol; membrane; extrinsic component of cytoplasmic side of plasma membrane; immunological synapse; extracellular exosome; pericentriolar material; membrane raft; plasma membrane;
Biological process	B cell receptor signaling pathway; release of sequestered calcium ion into cytosol; hemopoiesis; phosphorylation; transmembrane receptor protein tyrosine kinase signaling pathway; positive regulation of T cell receptor signaling pathway; T cell costimulation; mitigation of host defenses by virus; platelet activation; T cell differentiation; regulation of cell population proliferation; cellular zinc ion homeostasis; regulation of lymphocyte activation; peptidyl-tyrosine autophosphorylation; T cell receptor signaling pathway; positive regulation of intrinsic apoptotic signaling pathway; leukocyte migration; positive regulation of T cell activation; protein dephosphorylation; innate immune response; phosphatidylinositol phosphate biosynthetic process; viral process; protein phosphorylation; activation of cysteine-type endopeptidase activity involved in apoptotic process; cell migration; peptidyl-tyrosine phosphorylation; interleukin-7-mediated signaling pathway; positive regulation of protein kinase B signaling; cell differentiation; positive regulation of heterotypic cell-cell adhesion; positive regulation of leukocyte cell-cell adhesion;
	Sources:Amigo / QuickGO
Orthologs
	3932
	16818
	ENSG00000182866
	ENSMUSG00000000409
	P06239
	P06240
	NM_001042771; NM_005356; NM_001330468
	NM_001162432; NM_001162433; NM_010693
	NP_001036236; NP_001317397; NP_005347
	NP_001155904; NP_001155905; NP_034823
	Wikidata
View/Edit Human	View/Edit Mouse

Lck (or lymphocyte-specific protein tyrosine kinase) is a 56 kDa protein that is found inside specialized cells of the immune system called lymphocytes. The Lck is a member of Src kinase family (SFK), it is important for the activation of the T-cell receptor signaling in both naive T cells and effector T cells. The role of the Lck is less prominent in the activation or in the maintenance of memory CD8 T cells in comparison to CD4 T cells. In addition, the role of the lck varies among the memory T cells subsets. It seems that in mice, in the effector memory T cells (TEM) population, more than 50% of lck is present in a constitutively active conformation, whereas, only less than 20% of lck is present as active form of lck. These differences are due to differential regulation by SH2 domain–containing phosphatase-1 (Shp-1) and C-terminal Src kinase.

The Lck is responsible for the initiation of the TCR signaling cascade inside the cell by phosphorylating immunoreceptor tyrosine‑based activation motifs (ITAM) within the TCR-associated chains.

The Lck can be found in different forms in the immune cells: free in the cytosol or bound to the plasma membrane (PM) through myristoylation and palmitoylation. Due to the presence of the conserved CxxC motif (C20 and C23) in the zinc clasp structure, the Lck is able to bind the cell surface coreceptors CD8 and\or CD4.

Bound and free Lck have different properties: free Lck have more pronounced kinase activity in comparison to bounded Lck, moreover, the free form produces a higher T cell activation. The reasons of these differences are not well understood yet.

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