Scaffold protein that plays an important role in assembling signaling complexes downstream of several types of G protein-coupled receptors. Activates RHOA in response to signaling via G protein-coupled receptors via its function as Rho guanine nucleotide exchange factor. May also activate other Rho family members (PubMed:23658642). Part of a kinase signaling complex that links ADRA1A and ADRA1B adrenergic receptor signaling to the activation of downstream p38 MAP kinases, such as MAPK11 and MAPK14. Part of a signaling complex that links ADRA1B signaling to the activation of RHOA and IKBKB/IKKB, leading to increased NF-kappa-B transcriptional activity. Part of a RHOA-dependent signaling cascade that mediates responses to lysophosphatidic acid (LPA), a signaling molecule that activates G-protein coupled receptors and potentiates transcriptional activation of the glucocorticoid receptor NR3C1 (By similarity). Part of a signaling cascade that stimulates MEF2C-dependent gene expression in response to lysophosphatidic acid (LPA) (By similarity). Part of a signaling pathway that activates MAPK11 and/or MAPK14 and leads to increased transcription activation of the estrogen receptors ESR1 and ESR2. Part of a signaling cascade that links cAMP and EGFR signaling to BRAF signaling and to PKA-mediated phosphorylation of KSR1, leading to the activation of downstream MAP kinases, such as MAPK1 or MAPK3 (By similarity). Functions as scaffold protein that anchors cAMP-dependent protein kinase (PKA) and PRKD1. This promotes activation of PRKD1, leading to increased phosphorylation of HDAC5 and ultimately cardiomyocyte hypertrophy (PubMed:24161911). Has no guanine nucleotide exchange activity on CDC42, Ras or Rac (By similarity). Required for normal embryonic heart development, and in particular for normal sarcomere formation in the developing cardiomyocytes (PubMed:20139090). Plays a role in cardiomyocyte growth and cardiac hypertrophy in response to activation of the beta-adrenergic receptor by phenylephrine or isoproterenol (PubMed:23658642, PubMed:24161911). Required for normal adaptive cardiac hypertrophy in response to pressure overload (PubMed:17537920, PubMed:24161911). Plays a role in osteogenesis (PubMed:25892096). Interacts with the cAMP-dependent protein kinase (PKA) holoenzyme and with the regulatory subunit PRKAR2A (PubMed:21102438, PubMed:24161911, PubMed:23658642). Interacts with RHOA. Interacts also with RHOB and RHOC. Identified in a ternary complex with RHOA and PRKAR2A. Identified in a complex with NR3C1 and RHOA (By similarity). Interacts with BRAF and KSR1. Identified in a complex with BRAF and KSR1 (PubMed:21102438). Component of a signaling complex containing at least AKAP13, PKN1, MAPK14, ZAK and MAP2K3. Within this complex, AKAP13 interacts directly with PKN1, which in turn recruits MAPK14, MAP2K3 and ZAK. Interacts (phosphorylated form) with YWHAB and YWHAZ. Interaction with YWHAB inhibits activation of RHOA, interferes with PKN1 binding and activation of MAP kinases. Interacts with GNA12 (By similarity). Interacts with IKBKB (PubMed:23090968). Interacts with ESR1, THRA, PPARA and NME2 (By similarity). Interacts (via the C-terminal domain after the PH domain) with MEF2C and RXRB (PubMed:20139090). Interacts (via the C-terminal domain after the PH domain) with PRKD1 (PubMed:23658642, PubMed:24161911). Colocalizes with actin and myosin filaments in developing cardiomyocytes (PubMed:20139090). Colocalizes with the actin cytoskeleton at the cell cortex (By similarity). Detected in embryonic heart, limb bud, first branchial arch and forebrain (at protein level) (PubMed:20139090). Detected in heart (PubMed:20139090). Detected in perichondrium, but not in the bone growth plate (PubMed:25892096). Detected in head folds, notochord and somites at 8.5 dpc, with little or no expression in the looping heart. Detected in heart, vasculature, eye, ear, somites, gut and brain at 9.5 dpc. Expression in the heart increases by 10.5 dpc. Highly expressed in atrial and ventricular myocardium and endocardium, trabeculae and outflow tract at 14.5 dpc. Additionally, detected in skeletal muscle, tongue, gut, kidney, lung, urinary system and in the choroid plexus of the brain. Up-regulated in the left heart ventricle in response to phenylephrine. The DH domain is sufficient for interaction with RHOA, and for guanine nucleotide exchange (GEF) activity with RHOA. Forms that lack C-terminal regulatory domains have transforming activity and function as oncogenes. The PH domain does not play a role in lipid-binding. Instead, it inhibits the guanine nucleotide exchange (GEF) activity of the isolated DH domain (in vitro). The C-terminal domain after the PH domain is involved in protein-protein interactions that are required for normal, compensatory cardiac hypertrophy in response to pressure overload. Complete embryonic lethality (PubMed:16469733, PubMed:20139090). Mutant embryos are present at the expected Mendelian rate and develop normally up to 8 dpc. At 10 dpc, mutant embryos appear smaller, have an enlarged heart and pericardiac effusion. The myocardium is thinner than normal and has reduced trabeculation. Sarcomeres are abnormal with incompleteley formed myofilaments that end blindly and do not form Z-disks, indicating a defect in cardiomyocyte differentiation (PubMed:20139090). Heterozygous mice are born at the expected Mendelian frequency and appear grossly normal (PubMed:16469733, PubMed:20139090). Heterozygous mice display a blunted response to glucocorticoids (PubMed:16469733). Heterozygous mice display reduced bone volume relative to body size, but no change of bone length. Heterozygous mice display reduced bone mineral density and reduced trabecular bone, similar to osteoporotic bone. The number of osteoblasts in trabecular bone is reduced (PubMed:25892096).