PIK3AP1
Phosphoinositide-3-Kinase Adaptor Protein 1
Gene Information Card
| Symbol | PIK3AP1 |
|---|---|
| Full Name | Phosphoinositide-3-kinase adaptor protein 1 |
| Gene Type | protein-coding |
| Chromosomal Location | 10q24.1 |
| NCBI Gene ID | 118788 ncbi.nlm.nih.gov/gene/118788 |
| Ensembl ID | ENSG00000120063 |
| UniProt ID | Q6PFW1 |
| OMIM ID | 611399 |
| HGNC ID | 30034 |
| Aliases | BCAP, MGC131971 |
Description
PIK3AP1 encodes the B-cell adaptor for phosphoinositide 3-kinase (BCAP), a cytoplasmic protein that links B-cell receptor (BCR) and Toll-like receptor (TLR) signaling to the PI3K/AKT pathway. It contains YxxM motifs that recruit the p85 regulatory subunit of PI3K upon tyrosine phosphorylation, promoting cell survival, proliferation, and immune responses.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Immunodeficiency with B-cell defects | Impaired PI3K activation due to PIK3AP1 loss-of-function variants | PMID: 23541340 |
| Systemic lupus erythematosus (SLE) | Altered B-cell signaling and autoantibody production | PMID: 29127259 |
| Chronic lymphocytic leukemia (CLL) | Dysregulated PI3K/AKT signaling via BCAP overexpression | PMID: 25605293 |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Spleen | 12.5 | Medium |
| Lymph node | 10.8 | Medium |
| Bone marrow | 8.2 | Medium |
| Whole blood | 4.1 | Low |
| Lung | 2.3 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| Raji (B-lymphoblast) | 15.6 | High expression |
| Daudi (Burkitt lymphoma) | 14.2 | High expression |
| K-562 (leukemia) | 3.8 | Low expression |
| HeLa (cervical carcinoma) | 1.2 | Not detected |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.1132C>T (p.Arg378*) | Nonsense | <0.01% | Loss of function; truncated protein |
| c.1456G>A (p.Glu486Lys) | Missense | <0.01% | Unknown; predicted damaging |
| c.1720_1721del (p.Leu574fs) | Frameshift | <0.01% | Loss of function; premature stop |
Mutation functional classification
Loss of Function (LOF)
Nonsense and frameshift variants (e.g., p.Arg378*, p.Leu574fs) lead to truncated or absent BCAP protein, impairing PI3K recruitment and B-cell activation.
Gain of Function (GOF)
No confirmed gain-of-function variants reported in PIK3AP1.
Dominant Negative (DN)
No dominant-negative variants described for PIK3AP1.
View complete mutation data：
Gene Ontology (GO)
| • SH3/SH2 adaptor activity (GO:0005070) | • positive regulation of phosphatidylinositol 3-kinase signaling (GO:0043547) |
| • B cell receptor signaling pathway (GO:0050853) | • Fc-epsilon receptor signaling pathway (GO:0038095) |
| • cytoplasm (GO:0005737) |
Pathways
• PI3K/AKT signaling (Reactome: R-HSA-1257604)
• B cell receptor signaling (Reactome: R-HSA-983705)
• Toll-like receptor signaling (Reactome: R-HSA-168898)
Protein Summary
BCAP (PIK3AP1) is a 110 kDa adaptor protein predominantly expressed in B cells and myeloid cells. It contains an N-terminal coiled-coil domain, a proline-rich region, and multiple tyrosine phosphorylation sites (YxxM motifs). Upon BCR or TLR stimulation, BCAP is phosphorylated by Syk or Src-family kinases, creating docking sites for the p85 subunit of PI3K, leading to AKT activation. BCAP also interacts with the ubiquitin ligase Cbl-b to modulate immune receptor signaling.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| PIK3AP1 Knockout HEK293 Cell Line | EDJ-KQ843 | Human | 118788 | Details Get a Quote |
| PIK3AP1 Knockout A-549 Cell Line | EDJ-KQ19633 | Human | 118788 | Details Get a Quote |
| PIK3AP1 Knockout HCT 116 Cell Line | EDJ-KQ19634 | Human | 118788 | Details Get a Quote |
| PIK3AP1 Knockout HeLa Cell Line | EDJ-KQ58032 | Human | 118788 | Details Get a Quote |
