EphA2 Antibody – Rat Monoclonal

Function: Receptor tyrosine kinase which binds promiscuously membrane-bound ephrin-A family ligands residing on adjacent cells, leading to contact-dependent bidirectional signaling into neighboring cells. The signaling pathway downstream of the receptor is referred to as forward signaling while the signaling pathway downstream of the ephrin ligand is referred to as reverse signaling. Activated by the ligand ephrin-A1/EFNA1 regulates migration, integrin-mediated adhesion, proliferation and differentiation of cells. Regulates cell adhesion and differentiation through DSG1/desmoglein-1 and inhibition of the ERK1/ERK2 signaling pathway. May also participate in UV radiation-induced apoptosis and have a ligand-independent stimulatory effect on chemotactic cell migration. During development, may function in distinctive aspects of pattern formation and subsequently in development of several fetal tissues. Involved for instance in angiogenesis, in early hindbrain development and epithelial proliferation and branching morphogenesis during mammary gland development. Engaged by the ligand ephrin-A5/EFNA5 may regulate lens fiber cells shape and interactions and be important for lens transparency development and maintenance. With ephrin-A2/EFNA2 may play a role in bone remodeling through regulation of osteoclastogenesis and osteoblastogenesis. Ref.11 Ref.12 Ref.13 Ref.14 Ref.15 Ref.17 Ref.18

Catalytic activity: ATP + a [protein]-L-tyrosine = ADP + a [protein]-L-tyrosine phosphate. Ref.1

Subunit structure: Homodimer. Interacts with INPPL1; regulates activated EPHA2 endocytosis and degradation. Interacts (inactivated form) with PTK2/FAK1 and interacts (EFNA1 ligand-activated form) with PTPN11; regulates integrin-mediated adhesion. Interacts with ARHGEF16, DOCK4 and ELMO2; mediates ligand-independent activation of RAC1 which stimulates cell migration. Interacts with CLDN4; phosphorylates CLDN4 and may regulate tight junctions. Interacts with ACP1

By similarity. Interacts with SLA. Interacts (phosphorylated form) with VAV2, VAV3 and PI3-kinase p85 subunit (PIK3R1, PIK3R2 or PIK3R3); critical for the EFNA1-induced activation of RAC1 which stimulates cell migration. Interacts with ANKS1A. Ref.9 Ref.13 Ref.14 Ref.21

Subcellular location: Cell membrane; Single-pass type I membrane protein

By similarity. Cell projection › ruffle membrane; Single-pass type I membrane protein

By similarity. Cell projection › lamellipodium membrane; Single-pass type I membrane protein

By similarity. Cell junction › focal adhesion

By similarity. Note: Present at regions of cell-cell contacts but also at the leading edge of migrating cells

By similarity.

Tissue specificity: Expressed in the lung, intestine and liver. Ref.10

Developmental stage: First detected in gastrulation stage embryos (6.5-7.5 dpc) in ectodermal cells adjacent to the distal region of the primitive streak. By the neural plate stage (approximately 7.5 dpc), EPHA2 expression becomes restricted to the extreme distal end or node of the primitive streak. After the beginning of somitogenesis (approximately 8.0 dpc), expression persists in the node as this structure regresses toward the caudal end of the embryo. In addition, beginning at the mid head fold stage (approximately 7.75 dpc), we observe that EPHA2 exhibits a dynamic and spatially restricted expression pattern in the prospective hindbrain region. EPHA2 transcripts are initially detected in a 5-cell wide strip of mesodermal cells underlying prospective rhombomere 4 (R4). Subsequently at the beginning of somitogenesis, expression is observed in prospective R4. At the 4-8-somite stage, EPHA2 transcripts are observed in R4, mesenchymal cells underlying R4, and surface ectoderm in the vicinity of the developing second branchial arch. By the 10-somite stage, expression in these cells is down-regulated. Additionally, at the 5-8-somite stage, EPHA2 transcripts are detected initially in the lateral mesenchyme immediately underlying the surface ectoderm adjacent to R5 and R6, and subsequently in surface ectoderm overlying the developing third branchial arch. Ref.1 Ref.2 Ref.7 Ref.10

Post-translational modification: Autophosphorylates. Phosphorylated at Ser-898 by PKB; serum-induced phosphorylation which targets EPHA2 to the cell leading edge and stimulates cell migration. Phosphorylation by PKB is inhibited by EFNA1-activated EPHA2 which regulates PKB activity via a reciprocal regulatory loop. Dephosphorylated by ACP1

By similarity. Phosphorylated on tyrosine upon binding and activation by EFNA1. Phosphorylated residues Tyr-589 and Tyr-595 are required for binding VAV2 and VAV3 while phosphorylated residues Tyr-736 and Tyr-931 are required for binding PI3-kinase p85 subunit (PIK3R1, PIK3R2 or PIK3R3). These phosphorylated residues are critical for recruitment of VAV2 and VAV3 and PI3-kinase p85 subunit which transduce downstream signaling to activate RAC1 GTPase and cell migration

By similarity. Ref.14Ubiquitinated by CHIP/STUB1. Ubiquitination is regulated by the HSP90 chaperone and regulates the receptor stability and activity through proteasomal degradation. ANKS1A prevents ubiquitination and degradation. Ref.21

Disruption phenotype: Mice are viable, fertile but exhibit aberrant development of tail vertebra and susceptibility to carcinogenesis. Ref.10 Ref.11 Ref.12

Sequence similarities: Belongs to the protein kinase superfamily. Tyr protein kinase family. Ephrin receptor subfamily.Contains 1 Eph LBD (Eph ligand-binding) domain.Contains 2 fibronectin type-III domains.Contains 1 protein kinase domain.Contains 1 SAM (sterile alpha motif) domain.