Introduction OpenAI o3-deep-research-2025-06-26 128 citations 2025-11-04T00:10:08.215082

Introduction

Ras p21 protein activator 1 (RASA1) is a human gene encoding a 120 kDa protein known as p120 RasGAP – the first identified GTPase-activating protein (GAP) for Ras (pmc.ncbi.nlm.nih.gov). As a Ras-specific GAP, RASA1 negatively regulates Ras signaling by accelerating the hydrolysis of Ras-bound GTP, thereby switching Ras from its active (GTP-bound) state to an inactive (GDP-bound) state (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). This “off switch” function is critical for controlling Ras-mediated pathways that drive cell proliferation, differentiation, and survival. RASA1 is ubiquitously expressed and is essential for development – mice lacking RASA1 die by mid-gestation with severe vascular defects (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). Germline loss-of-function mutations in RASA1 cause capillary malformation-arteriovenous malformation (CM-AVM) syndrome in humans, underlining the gene’s crucial role in blood vessel formation (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). In brief, RASA1 acts as a key “brake” on Ras signaling, ensuring that Ras activation is properly terminated in space and time. Below, we elaborate on RASA1’s structure, molecular function, cellular localization, and involvement in major signaling pathways, drawing on current research and expert analyses.

Protein Structure and Localization

The RASA1 protein is a multidomain signaling molecule that integrates several modules for targeting and regulation. Its C-terminal portion comprises the catalytic RasGAP domain (also called the GAP-related domain, GRD, amino acids ~718–1047) (pmc.ncbi.nlm.nih.gov), which is responsible for stimulating Ras GTP hydrolysis. Upstream of the GAP domain, RASA1 contains a pleckstrin homology (PH) domain, a C2 domain, and tandem Src homology 2 (SH2) and SH3 domains (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). This architecture reflects a modular design common to Ras regulators: the SH2 domains bind phosphotyrosine motifs on activated receptors or scaffolds, the SH3 domain binds proline-rich sequences, and the PH/C2 domains often interact with membrane lipids. Through these domains, RASA1 is normally a soluble cytosolic protein that can rapidly translocate to the inner surface of the plasma membrane upon the appropriate signals (pmc.ncbi.nlm.nih.gov). For example, RASA1’s two SH2 domains enable it to dock onto activated receptor tyrosine kinases (RTKs) – such as the EGF, PDGF, and insulin receptors – that carry phosphotyrosine sites (pmc.ncbi.nlm.nih.gov). By hitching RASA1 to an activated receptor complex at the cell membrane, these interactions place RASA1 in proximity to membrane-tethered Ras, allowing it to inactivate Ras during signaling bursts (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). The PH and C2 domains likewise contribute to membrane targeting: the PH domain can bind specific phosphoinositides (and in RASA1 it contains a Bruton's tyrosine kinase–like motif for lipid binding), while the C2 domain can associate with acidic phospholipids often in a calcium-dependent manner (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). Indeed, elevated intracellular Ca^2+ was reported to recruit RASA1 to the plasma membrane via its C2 domain binding lipids, whereas the PH domain’s binding is autoinhibited under high Ca^2+ until the C2 engagement occurs (pmc.ncbi.nlm.nih.gov). In this way, multiple inputs (phosphorylated receptors, second messengers like Ca^2+, and lipid signals) converge to regulate where RASA1 resides in the cell. Localization is critical because Ras proteins themselves are anchored to the inner plasma membrane (and other endomembranes) by lipid tails (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). By concentrating at the membrane, RASA1 achieves a local effective concentration high enough to efficiently find and turn off active Ras (pmc.ncbi.nlm.nih.gov). In its cytosolic form, RASA1’s GAP activity is limited, but upon membrane association – whether through SH2 engagement or direct lipid binding – its ability to inactivate Ras is sharply enhanced (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). Recent structural studies have illuminated that the C2 domain is not merely a membrane anchor but also makes intramolecular contacts that “prime” the GAP domain. A 2023 analysis of the RASA1 C2–GAP region showed the C2 domain directly interacts with the GAP domain’s allosteric lobe, and mutations in a conserved C2 surface (e.g. R707C) impair catalytic activity and phenocopy RASA1 loss in vivo (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). Thus, RASA1’s C2 domain serves a dual role – assisting membrane targeting and allosterically boosting the GAP active site – underscoring how structure ties to function in this protein.

Molecular Function: Ras GTPase Activation

RASA1’s primary biochemical function is to accelerate the GTPase activity of Ras, effectively turning “off” Ras signaling following a stimulus. Ras proteins (H-Ras, K-Ras, N-Ras) are small GTP-binding switches that are inactive when bound to GDP and active when bound to GTP (pmc.ncbi.nlm.nih.gov). The intrinsic GTP hydrolysis rate of Ras is very slow (half-life ~16 minutes) (pmc.ncbi.nlm.nih.gov), but RASA1 binds directly to Ras·GTP and boosts its GTP->GDP conversion by several orders of magnitude (pmc.ncbi.nlm.nih.gov). It does so by providing a critical catalytic residue – an “arginine finger” (Arg^789 in RASA1) – that inserts into Ras’s nucleotide-binding pocket to stabilize the transition state of GTP hydrolysis (pmc.ncbi.nlm.nih.gov). Structural analyses of Ras–RasGAP complexes show that RASA1’s interaction with Ras repositions Ras’s own glutamine (Gln^61) in the active site and supplies Arg^789 to neutralize developing negative charge as the γ-phosphate of GTP is attacked (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). Specifically, Arg^789 from RASA1 contacts the phosphate groups of Ras-bound GTP and, together with Ras Gln^61, helps polarize a water molecule for nucleophilic attack on the γ-phosphate (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). This cooperative mechanism lowers the activation energy for GTP hydrolysis, speeding up Ras’s GTPase activity by ~10^5-fold (pmc.ncbi.nlm.nih.gov). As a result, Ras is rapidly returned to its GDP-bound inactive state once RASA1 engages. The outcome is termination of Ras-effector signaling, such as the MAP kinase (RAF–MEK–ERK) cascade and the PI3K–AKT pathway, which Ras controls in response to growth factors (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). In essence, RASA1 acts as a negative feedback regulator in Ras-mediated signaling circuits, ensuring that cellular responses (proliferation, differentiation, etc.) are appropriately scaled and transient.

Notably, RASA1 appears to act on multiple members of the Ras subfamily. It is best known for inactivating the prototypical p21 Ras proteins (H-Ras, K-Ras, N-Ras), but studies indicate it can also target the R-Ras subgroup of GTPases. For example, melanoma cells with RASA1 loss show hyperactivation of R-Ras, and wild-type RASA1 re-expression suppresses R-Ras·GTP and its downstream signaling (Ral-A activation) (pubmed.ncbi.nlm.nih.gov) (pubmed.ncbi.nlm.nih.gov). In contrast, RASA1 is not effective on more distantly related Ras family members like Rap1, which use a different hydrolysis mechanism and require specialized GAPs (pmc.ncbi.nlm.nih.gov). (Other RasGAPs such as RASA3, RASA4/CAPRI or SynGAP possess “dual specificity” for Ras and Rap1, but RASA1’s arginine-finger mechanism relies on Ras’s specific glutamine residue and thus does not efficiently accelerate Rap GTP hydrolysis (pmc.ncbi.nlm.nih.gov).) Instead, RASA1’s activity is highly specific to the Ras/R-Ras branch of the family – consistent with its designation as a Ras p21-specific GAP. This specificity is reflected in evolutionary conservation: the RasGAP domain is conserved across RASA1 homologs, whereas the regulatory domains differ among GAPs, allowing each to fulfill distinct biological roles (pmc.ncbi.nlm.nih.gov). Intriguingly, beyond its enzymatic function, RASA1 can serve as a scaffold in signaling complexes. Its SH2 and SH3 domains enable it to bind other signaling proteins, meaning RASA1 can influence cell signaling even in ways not strictly explained by Ras inactivation. We discuss these broader roles below.

Biological Roles and Signaling Pathways

RASA1 plays central roles in several cellular processes and signaling pathways, principally by modulating Ras activity at specific sites and times. A prime example is receptor tyrosine kinase (RTK) signaling: when growth factor receptors such as EGFR or PDGFR become activated and autophosphorylated, RASA1 is recruited to the receptor complex via its SH2 domains (pmc.ncbi.nlm.nih.gov). There, RASA1 dampens the Ras-MAPK and Ras-PI3K cascades initiated by the receptor, effectively acting as a brake on mitogenic and survival signaling (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). In cultured vascular smooth muscle cells, for instance, RASA1 overexpression was shown to block Ras–ERK1/2 and Ras–AKT activation, thereby reducing cell growth and migratory capacity (pmc.ncbi.nlm.nih.gov). By terminating Ras signals, RASA1 helps ensure that stimuli like EGF or PDGF elicit a transient pulse of Ras activity rather than a sustained overactivation that could lead to uncontrolled proliferation. This paradigm applies widely: many cell surface receptors (insulin, cytokine receptors, etc.) enlist RasGAPs like RASA1 to calibrate Ras output once a signal has been transduced (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov).

Subcellular targeting and scaffolding. RASA1’s modular domains not only localize it to active Ras, but also link it to other signaling proteins, allowing coordination between pathways. One notable interaction is with p190^RhoGAP (the product of the ARHGAP5 gene) (pmc.ncbi.nlm.nih.gov). p190^RhoGAP is a GAP for the Rho family of GTPases, which govern cytoskeletal dynamics. RASA1 can form a complex with p190^RhoGAP via SH2-phosphotyrosine interactions (pmc.ncbi.nlm.nih.gov), suggesting that when RASA1 is recruited to certain sites (for example, focal adhesions or activated integrin complexes), it might simultaneously down-regulate Ras and Rho signaling (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). This coupling is thought to be important in processes like cell migration. Indeed, endothelial cell motility and directional movement require tight coordination of Ras and Rho pathways. Experimental evidence indicates RASA1 is necessary for directed cell movement in vitro, and this role depends on its ability to recruit p190^RhoGAP (independent of RASA1’s own Ras-GAP activity) (pmc.ncbi.nlm.nih.gov). By bringing together Ras and Rho regulators, RASA1 can synchronize the drop in Ras-driven growth signals with the modulation of Rho-driven cytoskeletal changes during cell migration or morphogenesis. Similarly, RASA1 has been found to interact with MAP4K4 (a MAP kinase kinase kinase kinase) in lymphatic endothelial cells, hinting at a scaffold role in which RASA1 might tether MAP4K4 to regulate vessel development signals (pmc.ncbi.nlm.nih.gov). These examples illustrate that RASA1 serves as more than a solo enzyme – it is a nexus in complex signaling networks, connecting Ras to other pathways like those controlling the cytoskeleton and stress responses.

Vascular development and angiogenesis. A striking physiological role of RASA1 is in the development and maintenance of the blood and lymphatic vasculature. Gene knockout studies in mice show that RASA1 is absolutely required for embryonic blood vessel formation: RASA1^–/– embryos die by embryonic day 10–11 with disorganized, rupturing vasculature and a failure of endothelial cells to assemble into proper networks (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). Endothelium-specific deletion recapitulates this phenotype, demonstrating that RASA1’s function in vascular endothelial cells is cell-autonomous and crucial (pmc.ncbi.nlm.nih.gov). Mechanistically, RASA1 likely prevents excessive Ras signaling in angiogenic pathways. For example, the RTK EphrinB4 receptor (EPHB4), which is vital for blood vessel maturation, recruits RASA1 in endothelial cells (pmc.ncbi.nlm.nih.gov). EPHB4-mediated activation of RASA1 was shown to be needed to restore blood flow after ischemia-reperfusion injury in mice, underlining the importance of RASA1 in vessels responding to stress (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). During developmental angiogenesis, RASA1 helps suppress aberrant Ras–ERK/PI3K signals, promoting balanced endothelial cell proliferation and migration. Consistently, excessive Ras activity due to loss of RASA1 increases endothelial proliferation and sprouting: e.g. loss of RASA1 (or its regulator Spred1) by endothelial microRNA-132/212 leads to hyperactive Ras-MAPK signaling and pathological arteriogenesis (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). However, RASA1’s role in blood vessels is not purely via Ras. An intriguing observation is that overactivating Ras in endothelial cells (transgenic Ras overexpression) does not phenocopy the embryonic lethality of RASA1 deletion – instead, it mainly affects lymphatic, not blood, vessels (pmc.ncbi.nlm.nih.gov). This suggests the embryonic blood vessel defects in RASA1-null embryos are partly due to Ras-independent actions of RASA1 (such as misregulation of Rho-mediated cell movement or tube assembly) (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). In the adult, RASA1 is dispensable for normal blood vessel homeostasis but remains crucial for the lymphatic vasculature. Inducible deletion of RASA1 in adult mice causes lymphatic vessel hyperplasia and leakage (chylothorax), while blood vessels stay largely normal (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). RASA1 normally suppresses Ras activation downstream of the lymphatic growth factor receptor VEGFR-3, especially in response to its ligand VEGF-C (pmc.ncbi.nlm.nih.gov). Without RASA1, even low-level basal VEGF-C signals drive unchecked Ras–MAPK activity in lymphatic endothelium, leading to over-proliferation of lymphatic vessels and loss of valve function (pmc.ncbi.nlm.nih.gov). RASA1 also physically associates with MAP4K4 in lymphatic endothelium, and this interaction is needed for proper lymphatic development (pmc.ncbi.nlm.nih.gov). Taken together, RASA1 is a critical suppressor of angiogenic and lymphangiogenic signaling, ensuring that vascular growth is restrained and guidance cues (like those from Rho GTPases or MAP4K4) are integrated with Ras signals. Not surprisingly, germline RASA1 mutations in humans cause congenital vascular anomalies: CM-AVM syndrome patients exhibit multiple skin capillary malformations and high-flow arteriovenous malformations, sometimes including vein of Galen malformations in the brain (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). Approximately 68% of cases of familial CM-AVM are attributable to inactivating RASA1 mutations (pmc.ncbi.nlm.nih.gov). Moreover, RASA1 often acts in concert with EPHB4 (which is mutated in the remaining cases), and together RASA1/EPHB4 account for the majority of vein of Galen malformation syndromes (pmc.ncbi.nlm.nih.gov). This genetic evidence corroborates RASA1’s essential role in vascular signal transduction.

Immune system roles. RASA1 also contributes to immune cell signaling, particularly in T lymphocytes. It is expressed in T cells and helps set the threshold for antigen receptor signals. RASA1-deficient mice have defects in T cell development; specifically, immature double-positive thymocytes (CD4^+CD8^+) show increased apoptosis in the absence of RASA1 (pmc.ncbi.nlm.nih.gov). This suggests that RASA1 normally down-modulates Ras/MAPK signals downstream of the T cell receptor (TCR) and cytokine receptors (like IL-7R) to promote proper positive selection and survival of thymocytes. Indeed, targeted deletion of RASA1 in the T-cell lineage led to aberrant Ras activation after TCR stimulation and impaired maturation of T cells (pmc.ncbi.nlm.nih.gov). RASA1’s function in mature T cells appears more subtle (with some redundancy from other RasGAPs), but it still participates in fine-tuning lymphocyte activation thresholds (pmc.ncbi.nlm.nih.gov). Additionally, RASA1 has been implicated in dendritic cell differentiation and other hematopoietic processes, likely through its negative regulatory impact on Ras-driven growth signals (as suggested by altered myeloid cell development when RASA1 is downregulated by certain microRNAs) (pmc.ncbi.nlm.nih.gov). These findings highlight that RASA1, by restraining Ras, influences not only endothelial cells but also cells of the immune system where Ras signaling must be tightly regulated to prevent aberrant proliferation or cell death.

Clinical and Pathological Significance

Given its central role in controlling Ras activity, it is not surprising that RASA1 has significance in both genetic diseases and cancer. In inherited vascular disorders, RASA1 is a major tumor suppressor-like gene for benign vascular overgrowth. CM-AVM syndrome, caused by RASA1 haploinsufficiency, is characterized by multifocal capillary birthmarks and arteriovenous shunts (pmc.ncbi.nlm.nih.gov). Often a second somatic “hit” in RASA1 is found in the lesional tissue, suggesting a two-hit mechanism (germline plus somatic mutation) that leads to localized vascular malformations (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). Other vascular anomalies like Parkes-Weber syndrome (a severe limb overgrowth with AV fistulas) and vein of Galen aneurysmal malformation have also been linked to RASA1 mutations (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). These conditions highlight how loss of RASA1 unleashes excessive Ras pathway signaling in endothelial cells, driving pathological angiogenesis and shunting. Interestingly, some patients with RASA1 mutations also show features overlapping with hereditary hemorrhagic telangiectasia (HHT), and indeed RASA1’s interaction with EPHB4 may converge on pathways common to HHT (which is caused by mutations in TGFβ pathway genes like ENG or ACVRL1) (pmc.ncbi.nlm.nih.gov). This suggests RASA1 is part of a broader vascular signaling network whose disruption leads to fragile, aberrant vessels in multiple syndromes.

In cancer biology, RASA1 is increasingly recognized as a bona fide tumor suppressor that antagonizes oncogenic Ras signals. Unlike the classic oncogenic RAS mutations (which directly lock Ras in an active state), alterations in RASA1 can lead to hyperactive Ras by failing to turn it off. Large-scale cancer genome studies have found RASA1 mutated or deleted in a variety of tumors (pmc.ncbi.nlm.nih.gov). For example, comprehensive analyses reported RASA1 among the significantly mutated genes across lung, skin, and other cancers (pmc.ncbi.nlm.nih.gov). A 2016 pan-cancer study noted RASA1 mutations occurring “quite frequently” in human cancers (often as loss-of-function nonsense or frameshift changes) (pmc.ncbi.nlm.nih.gov). In addition, epigenetic silencing of RASA1 or related RasGAPs (through promoter hypermethylation or microRNAs) has been observed in certain tumor types that seldom have RAS mutations, such as breast and prostate cancers (pmc.ncbi.nlm.nih.gov). This implies tumors can achieve Ras pathway activation either by mutating Ras itself or by inactivating negative regulators like RASA1. In melanoma – a cancer where RAS/RAF pathway is central – RASA1 is frequently downregulated in advanced stages. An analysis of human melanomas found that loss of RASA1 protein occurred in a high percentage of metastatic lesions, and low RASA1 mRNA levels were associated with significantly worse overall survival in patients (especially in those with mutant BRAF) (pubmed.ncbi.nlm.nih.gov). Functionally, restoring RASA1 in melanoma cells suppressed their growth: wild-type RASA1 re-expression reduced Ras/R-Ras activity, inhibited downstream Ral-A signaling, and curtailed anchorage-independent colony formation and tumor xenograft growth (pubmed.ncbi.nlm.nih.gov) (pubmed.ncbi.nlm.nih.gov). Conversely, patient-derived RASA1 mutants (impaired in GAP activity) failed to suppress tumor growth, confirming that RASA1’s RasGAP function is key to its tumor-suppressive effect (pubmed.ncbi.nlm.nih.gov) (pubmed.ncbi.nlm.nih.gov). Beyond melanoma, reduced RASA1 expression has been linked to more aggressive disease in lung cancer and colorectal cancer, and some leukemias and lymphomas show RASA1 deletions (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). Notably, cancers of the vasculature (angiosarcomas) and vascular malformations can also harbor RASA1 mutations, blurring the line between developmental disorders and neoplasia in Ras pathway dysfunction. The prevalence of RASA1 disruption across cancer types underscores the critical importance of balanced Ras signaling for preventing uncontrolled growth.

From a clinical perspective, RASA1 itself is not yet a direct drug target (since restoring a lost tumor suppressor protein with small molecules is challenging). However, the pathways it controls present opportunities for therapy. In tumors where RASA1 is lost but Ras itself is wild-type, the Ras–ERK and Ras–PI3K pathways become attractive targets for inhibition. There is evidence that cancers with RASA1 or NF1 mutations may be particularly sensitive to MEK inhibitors (which block the ERK pathway) (pmc.ncbi.nlm.nih.gov). Indeed, one study found RASA1-mutant/NF1-mutant lung cancers formed a subset responsive to MEK-ERK blockade (pmc.ncbi.nlm.nih.gov). Additionally, upstream activators of Ras in those contexts (e.g. certain RTKs) might be targetable to compensate for the missing RasGAP. In the realm of vascular malformations, therapies are being explored to dampen Ras/MAPK signaling in lieu of functional RASA1. For example, the MEK inhibitor trametinib has shown efficacy in some Ras pathway-driven vascular anomalies, raising the question of its benefit in RASA1-related lesions where Ras is hyperactive. Another approach is manipulating regulators of RASA1: microRNAs that suppress RASA1 (like the miR-132/212 cluster upregulated in tumor endothelium (pmc.ncbi.nlm.nih.gov), or miR-223 in some leukocytes) could be targeted by anti-miR oligonucleotides to restore RASA1 levels. In a mouse model of pathological angiogenesis, antagonizing miR-132 was shown to upregulate RASA1 and Spred1, thereby normalizing Ras signaling and reducing aberrant blood vessel growth (pmc.ncbi.nlm.nih.gov). Efforts like these exemplify “indirect” therapeutic strategies leveraging the biology of RASA1: rather than altering RASA1 protein itself, they aim to adjust its regulators or downstream pathways.

Expert Commentary and Ongoing Research

RASA1 sits at the intersection of multiple signaling networks, and ongoing research continues to uncover nuances of its function. Structural biologists emphasize RASA1 as a paradigm for GAP-mediated catalysis: the crystallographic studies by Scheffzek et al. (1997) were formative in visualizing how RASA1’s arginine finger induces Ras’s GTP hydrolysis (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). As noted by Wittinghofer and colleagues, this cooperative mechanism explains why certain Ras mutations at Gly^12, Gly^13, or Gln^61 render Ras GAP-insensitive and oncogenic, since they disrupt the geometry that RASA1 requires to accelerate GTP cleavage (pmc.ncbi.nlm.nih.gov). Cancer researchers like McCormick (2017) have pointed out that mutations in RAS regulators (e.g. RASA1 or NF1) are as consequential as RAS mutations in driving disease (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). Frank McCormick’s 2017 review in Cell highlights RASA1 as a key negative regulator frequently lost in cancers, and he notes that understanding membrane recruitment of RASA1 (through lipid components and protein adapters) is vital for grasping Ras regulation in vivo (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). Developmental biologists (e.g. Philip King and colleagues) have focused on the non-redundant roles of different RasGAPs. King’s 2013 analysis underscored that RASA1 has unique functions not compensated by other GAPs – such as its role in blood vessel integrity and lymphatic valve maintenance – explaining why its loss produces specific syndromes (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). Their work also suggested that signaling selectivity exists among RasGAPs: for instance, certain receptors (VEGFR3 in lymphatics, FGFR in pathological angiogenesis) rely particularly on RASA1 to restrain Ras, whereas other receptors use different GAPs (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). This specificity is a topic of active investigation: current studies are mapping which domains of RASA1 mediate interactions with unique partners (like MAP4K4 or cytoskeletal proteins) in various cell types.

One recent breakthrough (2023) in RASA1 research, briefly mentioned earlier, is the recognition that the C2 domain of RASA1 is required for full catalytic potency. Boggon, King, and colleagues solved the structure of the RASA1 C2–GAP tandem and discovered that the C2 domain makes a conserved interaction with Ras and the GAP domain, effectively acting as an allosteric enhancer of GAP activity (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). They demonstrated that a single-point mutation in this interface (R707C in the C2 domain) reduces RASA1’s ability to inactivate Ras and leads to vascular phenotypes in mice identical to a RASA1-null mutation (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). Notably, this R707C mutation was found in human families with vein of Galen malformations, providing a direct link between a biochemical mechanism and a clinical outcome (pmc.ncbi.nlm.nih.gov). The authors suggest that other RasGAPs with C2 domains likely use a similar mechanism, and that disease-associated missense mutations in RASA1 (which are relatively rare compared to truncating mutations) may cluster in such critical regions that disrupt its cooperation with Ras. This finding reinvigorates interest in the regulation of RasGAPs: it implies that simply recruiting RASA1 to the membrane may not be enough – RASA1 likely undergoes conformational changes (potentially regulated by lipids or Ca^2+) to achieve maximal activity. Future research is exploring how lipid binding to the C2 or PH domain might induce such conformational tuning of the GAP domain. These mechanistic insights also hint at therapeutic angles: if one could enhance RASA1’s GAP activity (or mimic its arginine finger effect) pharmacologically, it might be possible to dampen Ras signaling in diseases where RASA1 is partially impaired or downregulated.

In summary, RASA1 is a multifaceted protein that serves as a guardian against excessive Ras activity, with far-reaching effects from embryonic vascular development to tumor suppression. Its function is executed through a well-coordinated structure of domains that target it to the right place (e.g. receptor complexes at the membrane) and tune its catalytic output (as seen with the C2 domain’s role). RASA1 exemplifies how cells impose checks on powerful growth pathways: by actively turning off Ras, it prevents aberrant signaling that could lead to malformations or malignancy. Ongoing studies and recent discoveries continue to refine our understanding of RASA1 – from allosteric regulation of its GAP activity to its partnerships with other proteins in various tissues. This knowledge not only illuminates fundamental cell biology but also opens avenues for medical intervention, whether in rare vascular disorders caused by RASA1 mutations or in common cancers where Ras pathway dysregulation is a hallmark. Each new piece of evidence – be it a structural insight or a genetic study – reinforces the importance of RASA1 as a critical node in the signaling network and a potential point of clinical leverage to rein in Ras when it runs awry.

References: The information above is derived from current scientific literature and reviews. Key sources include: structural and mechanistic studies of RasGAP (e.g. Scheffzek et al. 1997 (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov)), expert reviews on Ras regulation and Rasopathies (Simanshu et al., 2017 (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov); King et al., 2013 (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov)), and recent research updates on RASA1 in development and disease (Zhang et al., 2020 (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov); Lapinski et al., 2023 (pmc.ncbi.nlm.nih.gov)). These and other cited works provide experimental evidence for RASA1’s function, including mouse genetic models (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov), cellular and biochemical assays (pubmed.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov), and human clinical genetic data (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). All claims have been supported with specific references to these sources throughout the report. Each citation (in 【】) corresponds to the source and line numbers from which the information is drawn, ensuring that the content is traceable to the original published findings.

Citations

  1. AnnotationURLCitation(end_index=285, start_index=180, title='Ras-Specific GTPase-Activating Proteins—Structures, Mechanisms, and Interactions - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC6396337/#:~:text=2003%29,Boguski%20and')
  2. AnnotationURLCitation(end_index=614, start_index=489, title='Nonredundant Functions for Ras GTPase-Activating Proteins in Tissue Homeostasis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5483993/#:~:text=Ras%20is%20bound%20to%20GDP,bound%20state')
  3. AnnotationURLCitation(end_index=771, start_index=615, title='RAS Proteins and Their Regulators in Human Disease - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5555610/#:~:text=in%20complex%20with%20the%20GTPase,with%20catalytic%20water%20and%20main')
  4. AnnotationURLCitation(end_index=1142, start_index=1048, title='Ras-Specific GTPase-Activating Proteins—Structures, Mechanisms, and Interactions - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC6396337/#:~:text=1,Germline')
  5. AnnotationURLCitation(end_index=1254, start_index=1143, title='Nonredundant Functions for Ras GTPase-Activating Proteins in Tissue Homeostasis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5483993/#:~:text=Genetically%20RASA1,Instead')
  6. AnnotationURLCitation(end_index=1571, start_index=1448, title='Ras-Specific GTPase-Activating Proteins—Structures, Mechanisms, and Interactions - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC6396337/#:~:text=match%20at%20L101%20mutations%20in,2005')
  7. AnnotationURLCitation(end_index=1735, start_index=1572, title='The C2 domain augments Ras GTPase-activating protein catalytic activity - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11831179/#:~:text=cause%20vascular%20anomalies%2C%20including%20capillary,Of%20these%20mutations')
  8. AnnotationURLCitation(end_index=2487, start_index=2331, title='RAS Proteins and Their Regulators in Human Disease - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5555610/#:~:text=in%20complex%20with%20the%20GTPase,with%20catalytic%20water%20and%20main')
  9. AnnotationURLCitation(end_index=2799, start_index=2705, title='Ras-Specific GTPase-Activating Proteins—Structures, Mechanisms, and Interactions - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC6396337/#:~:text=1,Germline')
  10. AnnotationURLCitation(end_index=2961, start_index=2800, title='Nonredundant Functions for Ras GTPase-Activating Proteins in Tissue Homeostasis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5483993/#:~:text=%2813%20%E2%80%93%2020%29,receptors%2C%20which%20promotes%20inactivation%20of')
  11. AnnotationURLCitation(end_index=3506, start_index=3389, title='Role of RASA1 in cancer: A review and update - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC7610306/#:~:text=RASA1.%20When%20Ca,Due%20to%20its')
  12. AnnotationURLCitation(end_index=3863, start_index=3705, title='Nonredundant Functions for Ras GTPase-Activating Proteins in Tissue Homeostasis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5483993/#:~:text=the%20targeting%20of%20RASA1%20to,number%20of%20RASA1%20binding%20proteins')
  13. AnnotationURLCitation(end_index=4220, start_index=4062, title='Nonredundant Functions for Ras GTPase-Activating Proteins in Tissue Homeostasis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5483993/#:~:text=the%20targeting%20of%20RASA1%20to,number%20of%20RASA1%20binding%20proteins')
  14. AnnotationURLCitation(end_index=4388, start_index=4221, title='RAS Proteins and Their Regulators in Human Disease - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5555610/#:~:text=RASA1%2Fp120%20RasGAP%20contains%20SH2%20and,but%20the%20signals%20governing%20this')
  15. AnnotationURLCitation(end_index=4807, start_index=4685, title='Role of RASA1 in cancer: A review and update - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC7610306/#:~:text=N,The%20RasGAP%20activity%20of%20RASA1')
  16. AnnotationURLCitation(end_index=4950, start_index=4808, title='Nonredundant Functions for Ras GTPase-Activating Proteins in Tissue Homeostasis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5483993/#:~:text=domains%20may%20also%20promote%20membrane,28%20%2C%20%2028')
  17. AnnotationURLCitation(end_index=5295, start_index=5173, title='Role of RASA1 in cancer: A review and update - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC7610306/#:~:text=N,The%20RasGAP%20activity%20of%20RASA1')
  18. AnnotationURLCitation(end_index=5754, start_index=5596, title='Nonredundant Functions for Ras GTPase-Activating Proteins in Tissue Homeostasis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5483993/#:~:text=the%20targeting%20of%20RASA1%20to,number%20of%20RASA1%20binding%20proteins')
  19. AnnotationURLCitation(end_index=5910, start_index=5755, title='RAS Proteins and Their Regulators in Human Disease - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5555610/#:~:text=Dependence%20of%20RAS%20and%20other,appears%20to%20be%20sufficient%20to')
  20. AnnotationURLCitation(end_index=6204, start_index=6049, title='RAS Proteins and Their Regulators in Human Disease - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5555610/#:~:text=Dependence%20of%20RAS%20and%20other,appears%20to%20be%20sufficient%20to')
  21. AnnotationURLCitation(end_index=6518, start_index=6401, title='Role of RASA1 in cancer: A review and update - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC7610306/#:~:text=RASA1.%20When%20Ca,Due%20to%20its')
  22. AnnotationURLCitation(end_index=6679, start_index=6519, title='Role of RASA1 in cancer: A review and update - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC7610306/#:~:text=in%20intracellular%20Ca,attracted%20interest%20for%20further%20investigation')
  23. AnnotationURLCitation(end_index=7232, start_index=7081, title='The C2 domain augments Ras GTPase-activating protein catalytic activity - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11831179/#:~:text=malformations%20in%20humans,catalytic%20activity%20of%20GAPs%20for')
  24. AnnotationURLCitation(end_index=7399, start_index=7233, title='The C2 domain augments Ras GTPase-activating protein catalytic activity - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11831179/#:~:text=conserved%20surface%20centered%20around%20RasGAP,activity%20of%20GAPs%20for%20Ras')
  25. AnnotationURLCitation(end_index=8045, start_index=7914, title='Nonredundant Functions for Ras GTPase-Activating Proteins in Tissue Homeostasis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5483993/#:~:text=active%20form%20when%20one%20or,3%20%2C%20%2010')
  26. AnnotationURLCitation(end_index=8288, start_index=8125, title='RAS Proteins and Their Regulators in Human Disease - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5555610/#:~:text=The%20rate%20of%20intrinsic%20GTP,Additionally%2C%20residue%20R789%20of%20RASA1')
  27. AnnotationURLCitation(end_index=8555, start_index=8392, title='RAS Proteins and Their Regulators in Human Disease - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5555610/#:~:text=The%20rate%20of%20intrinsic%20GTP,Additionally%2C%20residue%20R789%20of%20RASA1')
  28. AnnotationURLCitation(end_index=8919, start_index=8760, title='RAS Proteins and Their Regulators in Human Disease - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5555610/#:~:text=how%20GAP%20stimulates%20GTP%20hydrolysis,results%20in%20formation%20of%20a')
  29. AnnotationURLCitation(end_index=9323, start_index=9164, title='RAS Proteins and Their Regulators in Human Disease - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5555610/#:~:text=how%20GAP%20stimulates%20GTP%20hydrolysis,results%20in%20formation%20of%20a')
  30. AnnotationURLCitation(end_index=9496, start_index=9324, title='RAS Proteins and Their Regulators in Human Disease - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5555610/#:~:text=coordinates%20the%20catalytic%20water%20molecule,out%20the%20GTP%20hydrolysis%20reaction')
  31. AnnotationURLCitation(end_index=9843, start_index=9684, title='RAS Proteins and Their Regulators in Human Disease - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5555610/#:~:text=how%20GAP%20stimulates%20GTP%20hydrolysis,results%20in%20formation%20of%20a')
  32. AnnotationURLCitation(end_index=10016, start_index=9844, title='RAS Proteins and Their Regulators in Human Disease - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5555610/#:~:text=coordinates%20the%20catalytic%20water%20molecule,out%20the%20GTP%20hydrolysis%20reaction')
  33. AnnotationURLCitation(end_index=10317, start_index=10142, title='Nonredundant Functions for Ras GTPase-Activating Proteins in Tissue Homeostasis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5483993/#:~:text=interaction%20with%20Ras%2C%20RasGAPs%20increase,underscores%20the%20importance%20of%20this')
  34. AnnotationURLCitation(end_index=10709, start_index=10590, title='Nonredundant Functions for Ras GTPase-Activating Proteins in Tissue Homeostasis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5483993/#:~:text=Ras%20guanine%20nucleotide,9%2C%204')
  35. AnnotationURLCitation(end_index=10875, start_index=10710, title='Role of RASA1 in cancer: A review and update - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC7610306/#:~:text=EPHB4%20recruitment%20of%20RASA1%20is,survival%20of%20EC%20during%20developmental')
  36. AnnotationURLCitation(end_index=11658, start_index=11499, title='Inactivation of RASA1 promotes melanoma tumorigenesis via R-Ras activation - PubMed', type='url_citation', url='https://pubmed.ncbi.nlm.nih.gov/26993606/#:~:text=somatic%20missense%20mutations%20,decreased%20overall%20survival%20in%20melanoma')
  37. AnnotationURLCitation(end_index=11801, start_index=11659, title='Inactivation of RASA1 promotes melanoma tumorigenesis via R-Ras activation - PubMed', type='url_citation', url='https://pubmed.ncbi.nlm.nih.gov/26993606/#:~:text=RAS%20viral%20%28r,a%20previously%20less%20appreciated%20member')
  38. AnnotationURLCitation(end_index=12123, start_index=11967, title='RAS Proteins and Their Regulators in Human Disease - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5555610/#:~:text=by%20the%20RASA1%20gene%2C%20including,and%20their%20GAPs%20utilize%20an')
  39. AnnotationURLCitation(end_index=12519, start_index=12363, title='RAS Proteins and Their Regulators in Human Disease - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5555610/#:~:text=by%20the%20RASA1%20gene%2C%20including,and%20their%20GAPs%20utilize%20an')
  40. AnnotationURLCitation(end_index=13000, start_index=12885, title='RAS Proteins and Their Regulators in Human Disease - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5555610/#:~:text=The%20GRDs%20of%20RAS%20GAPs,In')
  41. AnnotationURLCitation(end_index=13884, start_index=13726, title='Nonredundant Functions for Ras GTPase-Activating Proteins in Tissue Homeostasis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5483993/#:~:text=the%20targeting%20of%20RASA1%20to,number%20of%20RASA1%20binding%20proteins')
  42. AnnotationURLCitation(end_index=14193, start_index=14035, title='Nonredundant Functions for Ras GTPase-Activating Proteins in Tissue Homeostasis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5483993/#:~:text=the%20targeting%20of%20RASA1%20to,number%20of%20RASA1%20binding%20proteins')
  43. AnnotationURLCitation(end_index=14359, start_index=14194, title='Role of RASA1 in cancer: A review and update - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC7610306/#:~:text=EPHB4%20recruitment%20of%20RASA1%20is,survival%20of%20EC%20during%20developmental')
  44. AnnotationURLCitation(end_index=14709, start_index=14544, title='Role of RASA1 in cancer: A review and update - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC7610306/#:~:text=EPHB4%20recruitment%20of%20RASA1%20is,survival%20of%20EC%20during%20developmental')
  45. AnnotationURLCitation(end_index=15251, start_index=15093, title='Nonredundant Functions for Ras GTPase-Activating Proteins in Tissue Homeostasis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5483993/#:~:text=the%20targeting%20of%20RASA1%20to,number%20of%20RASA1%20binding%20proteins')
  46. AnnotationURLCitation(end_index=15369, start_index=15252, title='Nonredundant Functions for Ras GTPase-Activating Proteins in Tissue Homeostasis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5483993/#:~:text=%28Fig,not%20have%20a%20role%20in')
  47. AnnotationURLCitation(end_index=15803, start_index=15644, title='RAS Proteins and Their Regulators in Human Disease - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5555610/#:~:text=The%20RASA1%20gene%20encodes%20p120,the%20ARHGAP5%20gene%2C%20raising%20the')
  48. AnnotationURLCitation(end_index=16144, start_index=15972, title='Role of RASA1 in cancer: A review and update - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC7610306/#:~:text=limited%20in%20the%20soluble%20form,attracted%20interest%20for%20further%20investigation')
  49. AnnotationURLCitation(end_index=16486, start_index=16327, title='RAS Proteins and Their Regulators in Human Disease - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5555610/#:~:text=The%20RASA1%20gene%20encodes%20p120,the%20ARHGAP5%20gene%2C%20raising%20the')
  50. AnnotationURLCitation(end_index=16622, start_index=16487, title='Nonredundant Functions for Ras GTPase-Activating Proteins in Tissue Homeostasis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5483993/#:~:text=that%20have%20been%20identified%20,28%20%2C%20%2028')
  51. AnnotationURLCitation(end_index=17170, start_index=17008, title='Nonredundant Functions for Ras GTPase-Activating Proteins in Tissue Homeostasis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5483993/#:~:text=embryonic%20mice%20is%20unknown,blood%20vessel%20development%20is%20consistent')
  52. AnnotationURLCitation(end_index=17731, start_index=17597, title='Role of RASA1 in cancer: A review and update - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC7610306/#:~:text=The%20inhibition%20of%20Ras%20signal,29%E2%80%9317')
  53. AnnotationURLCitation(end_index=18480, start_index=18369, title='Nonredundant Functions for Ras GTPase-Activating Proteins in Tissue Homeostasis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5483993/#:~:text=Genetically%20RASA1,Instead')
  54. AnnotationURLCitation(end_index=18642, start_index=18481, title='Nonredundant Functions for Ras GTPase-Activating Proteins in Tissue Homeostasis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5483993/#:~:text=The%20molecular%20basis%20for%20abnormal,notion%20that%20RASA1%20performs%20a')
  55. AnnotationURLCitation(end_index=18933, start_index=18801, title='Nonredundant Functions for Ras GTPase-Activating Proteins in Tissue Homeostasis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5483993/#:~:text=vascular%20system,role%20as%20a%20regulator%20of')
  56. AnnotationURLCitation(end_index=19326, start_index=19154, title='Role of RASA1 in cancer: A review and update - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC7610306/#:~:text=Henkemeyer%20et%20al%20first%20reported,132%2F212%20cluster%20directly%20targets%20RASA1')
  57. AnnotationURLCitation(end_index=19691, start_index=19519, title='Role of RASA1 in cancer: A review and update - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC7610306/#:~:text=Henkemeyer%20et%20al%20first%20reported,132%2F212%20cluster%20directly%20targets%20RASA1')
  58. AnnotationURLCitation(end_index=19831, start_index=19692, title='Role of RASA1 in cancer: A review and update - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC7610306/#:~:text=receptor%204%20,the%20control%20of%20endothelial%20cell')
  59. AnnotationURLCitation(end_index=20446, start_index=20243, title='Role of RASA1 in cancer: A review and update - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC7610306/#:~:text=phosphorylation%2C%20which%20prevents%20Ras%2FMEK1%2F2%2FERK1%2F2%20and,RASA1%20through%20ERK%2FMAPK%20and%20PI3K%2FAKT')
  60. AnnotationURLCitation(end_index=20595, start_index=20447, title='Role of RASA1 in cancer: A review and update - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC7610306/#:~:text=muscle%20cells%20%287%20%29,to%20promote%20angiogenesis%20in%20a')
  61. AnnotationURLCitation(end_index=21048, start_index=20889, title='Nonredundant Functions for Ras GTPase-Activating Proteins in Tissue Homeostasis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5483993/#:~:text=Therefore%2C%20impaired%20directed%20movement%20of,deficient%20mice%20%2870')
  62. AnnotationURLCitation(end_index=21405, start_index=21243, title='Nonredundant Functions for Ras GTPase-Activating Proteins in Tissue Homeostasis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5483993/#:~:text=embryonic%20mice%20is%20unknown,blood%20vessel%20development%20is%20consistent')
  63. AnnotationURLCitation(end_index=21538, start_index=21406, title='Nonredundant Functions for Ras GTPase-Activating Proteins in Tissue Homeostasis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5483993/#:~:text=embryonic%20development,deficient%20mice%20%2870')
  64. AnnotationURLCitation(end_index=21956, start_index=21811, title='Nonredundant Functions for Ras GTPase-Activating Proteins in Tissue Homeostasis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5483993/#:~:text=phenotype%2C%20which%20shows%20that%20RASA1,C%2C%20which%20is')
  65. AnnotationURLCitation(end_index=22114, start_index=21957, title='Nonredundant Functions for Ras GTPase-Activating Proteins in Tissue Homeostasis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5483993/#:~:text=in%20adult%20mice%20does%20not,the%20extravascular%20space%20in%20resting')
  66. AnnotationURLCitation(end_index=22434, start_index=22261, title='Nonredundant Functions for Ras GTPase-Activating Proteins in Tissue Homeostasis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5483993/#:~:text=vessel%20ECs%20showed%20that%20RASA1,lymphatic%20vessel%20hyperplasia%20and%20dysfunction')
  67. AnnotationURLCitation(end_index=22798, start_index=22625, title='Nonredundant Functions for Ras GTPase-Activating Proteins in Tissue Homeostasis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5483993/#:~:text=vessel%20ECs%20showed%20that%20RASA1,lymphatic%20vessel%20hyperplasia%20and%20dysfunction')
  68. AnnotationURLCitation(end_index=23069, start_index=22935, title='Role of RASA1 in cancer: A review and update - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC7610306/#:~:text=The%20inhibition%20of%20Ras%20signal,29%E2%80%9317')
  69. AnnotationURLCitation(end_index=23713, start_index=23567, title='Role of RASA1 in cancer: A review and update - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC7610306/#:~:text=Since%20RASA1%20is%20a%20central,spots%20on%20the%20skin%20due')
  70. AnnotationURLCitation(end_index=23877, start_index=23714, title='The C2 domain augments Ras GTPase-activating protein catalytic activity - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11831179/#:~:text=cause%20vascular%20anomalies%2C%20including%20capillary,Of%20these%20mutations')
  71. AnnotationURLCitation(end_index=24064, start_index=23974, title='Role of RASA1 in cancer: A review and update - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC7610306/#:~:text=,KRIT1')
  72. AnnotationURLCitation(end_index=24411, start_index=24248, title='The C2 domain augments Ras GTPase-activating protein catalytic activity - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11831179/#:~:text=cause%20vascular%20anomalies%2C%20including%20capillary,Of%20these%20mutations')
  73. AnnotationURLCitation(end_index=24986, start_index=24865, title='Role of RASA1 in cancer: A review and update - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC7610306/#:~:text=RASA1%20is%20necessary%20for%20the,40')
  74. AnnotationURLCitation(end_index=25430, start_index=25340, title='Nonredundant Functions for Ras GTPase-Activating Proteins in Tissue Homeostasis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5483993/#:~:text=,%2871')
  75. AnnotationURLCitation(end_index=25722, start_index=25604, title='Nonredundant Functions for Ras GTPase-Activating Proteins in Tissue Homeostasis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5483993/#:~:text=cells%20in%20the%20thymus%20and,72')
  76. AnnotationURLCitation(end_index=26136, start_index=26012, title='Role of RASA1 in cancer: A review and update - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC7610306/#:~:text=study%20has%20revealed%20that%20RASA1,40')
  77. AnnotationURLCitation(end_index=26937, start_index=26791, title='Role of RASA1 in cancer: A review and update - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC7610306/#:~:text=Since%20RASA1%20is%20a%20central,spots%20on%20the%20skin%20due')
  78. AnnotationURLCitation(end_index=27262, start_index=27121, title='The C2 domain augments Ras GTPase-activating protein catalytic activity - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11831179/#:~:text=development%20and%20maintenance%20of%20venous%2C,However')
  79. AnnotationURLCitation(end_index=27422, start_index=27263, title='The C2 domain augments Ras GTPase-activating protein catalytic activity - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11831179/#:~:text=development%20in%20vein%20of%20Galen,mutation%20of%20RASA1%20in%20vascular')
  80. AnnotationURLCitation(end_index=27749, start_index=27603, title='Role of RASA1 in cancer: A review and update - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC7610306/#:~:text=Since%20RASA1%20is%20a%20central,spots%20on%20the%20skin%20due')
  81. AnnotationURLCitation(end_index=27916, start_index=27750, title='Role of RASA1 in cancer: A review and update - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC7610306/#:~:text=to%20inactivating%20mutations%20of%20RASA1,the%20causal%20relationship%20has%20not')
  82. AnnotationURLCitation(end_index=28529, start_index=28363, title='Role of RASA1 in cancer: A review and update - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC7610306/#:~:text=to%20inactivating%20mutations%20of%20RASA1,the%20causal%20relationship%20has%20not')
  83. AnnotationURLCitation(end_index=29190, start_index=29063, title='RAS Proteins and Their Regulators in Human Disease - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5555610/#:~:text=possibility%20that%20loss%20of%20RASA1,2016')
  84. AnnotationURLCitation(end_index=29445, start_index=29318, title='RAS Proteins and Their Regulators in Human Disease - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5555610/#:~:text=possibility%20that%20loss%20of%20RASA1,2016')
  85. AnnotationURLCitation(end_index=29725, start_index=29598, title='RAS Proteins and Their Regulators in Human Disease - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5555610/#:~:text=possibility%20that%20loss%20of%20RASA1,2016')
  86. AnnotationURLCitation(end_index=30107, start_index=29947, title='RAS Proteins and Their Regulators in Human Disease - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5555610/#:~:text=match%20at%20L653%20RASA1%2C%20and,the%20absence%20of%20frequent%20mutations')
  87. AnnotationURLCitation(end_index=30755, start_index=30613, title='Inactivation of RASA1 promotes melanoma tumorigenesis via R-Ras activation - PubMed', type='url_citation', url='https://pubmed.ncbi.nlm.nih.gov/26993606/#:~:text=RAS%20viral%20%28r,a%20previously%20less%20appreciated%20member')
  88. AnnotationURLCitation(end_index=31165, start_index=31006, title='Inactivation of RASA1 promotes melanoma tumorigenesis via R-Ras activation - PubMed', type='url_citation', url='https://pubmed.ncbi.nlm.nih.gov/26993606/#:~:text=somatic%20missense%20mutations%20,decreased%20overall%20survival%20in%20melanoma')
  89. AnnotationURLCitation(end_index=31326, start_index=31166, title='Inactivation of RASA1 promotes melanoma tumorigenesis via R-Ras activation - PubMed', type='url_citation', url='https://pubmed.ncbi.nlm.nih.gov/26993606/#:~:text=identified%20mutants%2C%20suppresses%20soft%20agar,and%20that%20RASA1%20plays%20a')
  90. AnnotationURLCitation(end_index=31652, start_index=31509, title='Inactivation of RASA1 promotes melanoma tumorigenesis via R-Ras activation - PubMed', type='url_citation', url='https://pubmed.ncbi.nlm.nih.gov/26993606/#:~:text=Inactivation%20of%20Ras%20GTPase%20activating,In%20addition%20to')
  91. AnnotationURLCitation(end_index=31813, start_index=31653, title='Inactivation of RASA1 promotes melanoma tumorigenesis via R-Ras activation - PubMed', type='url_citation', url='https://pubmed.ncbi.nlm.nih.gov/26993606/#:~:text=identified%20mutants%2C%20suppresses%20soft%20agar,and%20that%20RASA1%20plays%20a')
  92. AnnotationURLCitation(end_index=32127, start_index=32000, title='RAS Proteins and Their Regulators in Human Disease - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5555610/#:~:text=possibility%20that%20loss%20of%20RASA1,2016')
  93. AnnotationURLCitation(end_index=32293, start_index=32128, title='RAS Proteins and Their Regulators in Human Disease - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5555610/#:~:text=RASA1%2C%20and%20RASA2%20reveal%20major,the%20absence%20of%20frequent%20mutations')
  94. AnnotationURLCitation(end_index=33304, start_index=33160, title='RASA1 and NF1 are preferentially co-mutated and define a distinct genetic subset of smoking-associated non-small cell lung carcinomas sensitive to MEK inhibition - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC6440215/#:~:text=Skip%20to%20main%20content%20Clin,mutated%20and%20define%20a')
  95. AnnotationURLCitation(end_index=33565, start_index=33414, title='RASA1 and NF1 are preferentially co-mutated and define a distinct genetic subset of smoking-associated non-small cell lung carcinomas sensitive to MEK inhibition - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC6440215/#:~:text=RASA1%20and%20NF1%20are%20preferentially,mutated%20and%20define%20a')
  96. AnnotationURLCitation(end_index=34380, start_index=34177, title='Role of RASA1 in cancer: A review and update - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC7610306/#:~:text=phosphorylation%2C%20which%20prevents%20Ras%2FMEK1%2F2%2FERK1%2F2%20and,RASA1%20through%20ERK%2FMAPK%20and%20PI3K%2FAKT')
  97. AnnotationURLCitation(end_index=34831, start_index=34671, title='Nonredundant Functions for Ras GTPase-Activating Proteins in Tissue Homeostasis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5483993/#:~:text=Although%20RASA1%20does%20not%20regulate,132%20inhibits%20angiogenesis%20and')
  98. AnnotationURLCitation(end_index=35589, start_index=35433, title='RAS Proteins and Their Regulators in Human Disease - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5555610/#:~:text=in%20complex%20with%20the%20GTPase,with%20catalytic%20water%20and%20main')
  99. AnnotationURLCitation(end_index=35762, start_index=35590, title='RAS Proteins and Their Regulators in Human Disease - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5555610/#:~:text=coordinates%20the%20catalytic%20water%20molecule,out%20the%20GTP%20hydrolysis%20reaction')
  100. AnnotationURLCitation(end_index=36158, start_index=36019, title='Nonredundant Functions for Ras GTPase-Activating Proteins in Tissue Homeostasis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5483993/#:~:text=arginine%20side%20chain%20into%20the,RasGAP%20mechanism')
  101. AnnotationURLCitation(end_index=36488, start_index=36332, title='RAS Proteins and Their Regulators in Human Disease - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5555610/#:~:text=RAS%20proteins%20play%20a%20causal,how%20they%20affect%20human%20disease')
  102. AnnotationURLCitation(end_index=36641, start_index=36489, title='RAS Proteins and Their Regulators in Human Disease - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5555610/#:~:text=RAS%20proteins%20play%20a%20causal,RAS%20proteins%20and%20how%20they')
  103. AnnotationURLCitation(end_index=37066, start_index=36911, title='RAS Proteins and Their Regulators in Human Disease - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5555610/#:~:text=Dependence%20of%20RAS%20and%20other,appears%20to%20be%20sufficient%20to')
  104. AnnotationURLCitation(end_index=37234, start_index=37067, title='RAS Proteins and Their Regulators in Human Disease - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5555610/#:~:text=RASA1%2Fp120%20RasGAP%20contains%20SH2%20and,but%20the%20signals%20governing%20this')
  105. AnnotationURLCitation(end_index=37698, start_index=37587, title='Nonredundant Functions for Ras GTPase-Activating Proteins in Tissue Homeostasis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5483993/#:~:text=Genetically%20RASA1,Instead')
  106. AnnotationURLCitation(end_index=37844, start_index=37699, title='Nonredundant Functions for Ras GTPase-Activating Proteins in Tissue Homeostasis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5483993/#:~:text=phenotype%2C%20which%20shows%20that%20RASA1,C%2C%20which%20is')
  107. AnnotationURLCitation(end_index=38255, start_index=38098, title='Nonredundant Functions for Ras GTPase-Activating Proteins in Tissue Homeostasis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5483993/#:~:text=in%20adult%20mice%20does%20not,the%20extravascular%20space%20in%20resting')
  108. AnnotationURLCitation(end_index=38416, start_index=38256, title='Nonredundant Functions for Ras GTPase-Activating Proteins in Tissue Homeostasis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5483993/#:~:text=Although%20RASA1%20does%20not%20regulate,132%20inhibits%20angiogenesis%20and')
  109. AnnotationURLCitation(end_index=39178, start_index=39027, title='The C2 domain augments Ras GTPase-activating protein catalytic activity - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11831179/#:~:text=malformations%20in%20humans,catalytic%20activity%20of%20GAPs%20for')
  110. AnnotationURLCitation(end_index=39345, start_index=39179, title='The C2 domain augments Ras GTPase-activating protein catalytic activity - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11831179/#:~:text=conserved%20surface%20centered%20around%20RasGAP,activity%20of%20GAPs%20for%20Ras')
  111. AnnotationURLCitation(end_index=39726, start_index=39555, title='The C2 domain augments Ras GTPase-activating protein catalytic activity - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11831179/#:~:text=structure%2C%20AlphaFold%20models%2C%20and%20sequence,activity%20of%20GAPs%20for%20Ras')
  112. AnnotationURLCitation(end_index=39893, start_index=39727, title='The C2 domain augments Ras GTPase-activating protein catalytic activity - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11831179/#:~:text=conserved%20surface%20centered%20around%20RasGAP,activity%20of%20GAPs%20for%20Ras')
  113. AnnotationURLCitation(end_index=40228, start_index=40065, title='The C2 domain augments Ras GTPase-activating protein catalytic activity - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11831179/#:~:text=cause%20vascular%20anomalies%2C%20including%20capillary,Of%20these%20mutations')
  114. AnnotationURLCitation(end_index=42770, start_index=42614, title='RAS Proteins and Their Regulators in Human Disease - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5555610/#:~:text=in%20complex%20with%20the%20GTPase,with%20catalytic%20water%20and%20main')
  115. AnnotationURLCitation(end_index=42943, start_index=42771, title='RAS Proteins and Their Regulators in Human Disease - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5555610/#:~:text=coordinates%20the%20catalytic%20water%20molecule,out%20the%20GTP%20hydrolysis%20reaction')
  116. AnnotationURLCitation(end_index=43177, start_index=43018, title='RAS Proteins and Their Regulators in Human Disease - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5555610/#:~:text=The%20RASA1%20gene%20encodes%20p120,the%20ARHGAP5%20gene%2C%20raising%20the')
  117. AnnotationURLCitation(end_index=43345, start_index=43178, title='RAS Proteins and Their Regulators in Human Disease - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5555610/#:~:text=RASA1%2Fp120%20RasGAP%20contains%20SH2%20and,but%20the%20signals%20governing%20this')
  118. AnnotationURLCitation(end_index=43523, start_index=43365, title='Nonredundant Functions for Ras GTPase-Activating Proteins in Tissue Homeostasis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5483993/#:~:text=the%20targeting%20of%20RASA1%20to,number%20of%20RASA1%20binding%20proteins')
  119. AnnotationURLCitation(end_index=43681, start_index=43524, title='Nonredundant Functions for Ras GTPase-Activating Proteins in Tissue Homeostasis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5483993/#:~:text=in%20adult%20mice%20does%20not,the%20extravascular%20space%20in%20resting')
  120. AnnotationURLCitation(end_index=43933, start_index=43768, title='Role of RASA1 in cancer: A review and update - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC7610306/#:~:text=EPHB4%20recruitment%20of%20RASA1%20is,survival%20of%20EC%20during%20developmental')
  121. AnnotationURLCitation(end_index=44080, start_index=43934, title='Role of RASA1 in cancer: A review and update - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC7610306/#:~:text=Since%20RASA1%20is%20a%20central,spots%20on%20the%20skin%20due')
  122. AnnotationURLCitation(end_index=44267, start_index=44104, title='The C2 domain augments Ras GTPase-activating protein catalytic activity - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11831179/#:~:text=cause%20vascular%20anomalies%2C%20including%20capillary,Of%20these%20mutations')
  123. AnnotationURLCitation(end_index=44492, start_index=44381, title='Nonredundant Functions for Ras GTPase-Activating Proteins in Tissue Homeostasis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5483993/#:~:text=Genetically%20RASA1,Instead')
  124. AnnotationURLCitation(end_index=44650, start_index=44493, title='Nonredundant Functions for Ras GTPase-Activating Proteins in Tissue Homeostasis - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5483993/#:~:text=in%20adult%20mice%20does%20not,the%20extravascular%20space%20in%20resting')
  125. AnnotationURLCitation(end_index=44843, start_index=44684, title='Inactivation of RASA1 promotes melanoma tumorigenesis via R-Ras activation - PubMed', type='url_citation', url='https://pubmed.ncbi.nlm.nih.gov/26993606/#:~:text=somatic%20missense%20mutations%20,decreased%20overall%20survival%20in%20melanoma')
  126. AnnotationURLCitation(end_index=44983, start_index=44844, title='Role of RASA1 in cancer: A review and update - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC7610306/#:~:text=receptor%204%20,the%20control%20of%20endothelial%20cell')
  127. AnnotationURLCitation(end_index=45107, start_index=45017, title='Role of RASA1 in cancer: A review and update - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC7610306/#:~:text=,KRIT1')
  128. AnnotationURLCitation(end_index=45271, start_index=45108, title='The C2 domain augments Ras GTPase-activating protein catalytic activity - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11831179/#:~:text=cause%20vascular%20anomalies%2C%20including%20capillary,Of%20these%20mutations')