A-kinase anchor protein 13; AKAP-13; AKAP-Lbc; breast cancer nuclear receptor-binding auxiliary protein; guanine nucleotide exchange factor Lbc; human thyroid-anchoring protein 31; lymphoid blast crisis oncogene; LBC oncogene; non-oncogenic Rho GTPase-specific GTP exchange factor; protein kinase A-anchoring protein 13; p47 (AKAP13, BRX, HT31, LBC)
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Function
- anchors cAMP-dependent protein kinase (PKA)
- acts as an adapter protein to selectively couple G alpha-13 & Rho
- augments gene activation by the estrogen receptor (element-specific, ligand-dependent)
- activates estrogen receptor beta by a p38 MAPK-dependent pathway
- isoform 6 stimulates exchange activity on Rho proteins in vitro, but not on CDC42, Ras or Rac
- may bind Ca+2
- binds cAMP-dependent protein kinase (PKA) & to the RII-alpha regulatory subunit of PKA
- interacts with ESR1, ESR2, THRA, PPARA, RHOA & NME2
Structure
- both the DH & PH domains are required for transforming activity
- contains 1 DH (DBL-homology) domain
- contains 1 PH domain
- contains 1 phorbol-ester/DAG-type Zn+2 finger
Compartment
Alternative splicing
named isoforms=7
Expression
- isoform 3 & isoform 6
- expressed in hematopoietic cells, skeletal muscle, lung, heart, estrogen- responsive reproductive tissues, including breast ductal epithelium
- also found in testis & breast cancer cell lines
- isoform 6 is not found in brain, placenta, liver, pancreas or kidney
- isoform 7 is expressed in myeloid & lymphoid lineages, a variety of epithelial tissues & skeletal muscle
- isoform 2
- predominantly expressed in the heart
- lower expression in lung, placenta, kidney, pancreas, skeletal muscle & liver