diff --git a/contracts/interfaces/IMain.sol b/contracts/interfaces/IMain.sol
index f7f2c9bd6..876b4e801 100644
--- a/contracts/interfaces/IMain.sol
+++ b/contracts/interfaces/IMain.sol
@@ -156,6 +156,8 @@ interface IComponentRegistry {
     event BrokerSet(IBroker oldVal, IBroker newVal);
 
     function broker() external view returns (IBroker);
+
+    function isComponent(address addr) external view returns (bool);
 }
 
 /**
diff --git a/contracts/mixins/ComponentRegistry.sol b/contracts/mixins/ComponentRegistry.sol
index ff3a29f7c..0bafd742c 100644
--- a/contracts/mixins/ComponentRegistry.sol
+++ b/contracts/mixins/ComponentRegistry.sol
@@ -35,6 +35,7 @@ abstract contract ComponentRegistry is Initializable, Auth, IComponentRegistry {
     function _setRToken(IRToken val) private {
         require(address(val) != address(0), "invalid RToken address");
         emit RTokenSet(rToken, val);
+        isComponent[address(val)] = true;
         rToken = val;
     }
 
@@ -43,6 +44,7 @@ abstract contract ComponentRegistry is Initializable, Auth, IComponentRegistry {
     function _setStRSR(IStRSR val) private {
         require(address(val) != address(0), "invalid StRSR address");
         emit StRSRSet(stRSR, val);
+        isComponent[address(val)] = true;
         stRSR = val;
     }
 
@@ -51,6 +53,7 @@ abstract contract ComponentRegistry is Initializable, Auth, IComponentRegistry {
     function _setAssetRegistry(IAssetRegistry val) private {
         require(address(val) != address(0), "invalid AssetRegistry address");
         emit AssetRegistrySet(assetRegistry, val);
+        isComponent[address(val)] = true;
         assetRegistry = val;
     }
 
@@ -59,6 +62,7 @@ abstract contract ComponentRegistry is Initializable, Auth, IComponentRegistry {
     function _setBasketHandler(IBasketHandler val) private {
         require(address(val) != address(0), "invalid BasketHandler address");
         emit BasketHandlerSet(basketHandler, val);
+        isComponent[address(val)] = true;
         basketHandler = val;
     }
 
@@ -67,6 +71,7 @@ abstract contract ComponentRegistry is Initializable, Auth, IComponentRegistry {
     function _setBackingManager(IBackingManager val) private {
         require(address(val) != address(0), "invalid BackingManager address");
         emit BackingManagerSet(backingManager, val);
+        isComponent[address(val)] = true;
         backingManager = val;
     }
 
@@ -75,6 +80,7 @@ abstract contract ComponentRegistry is Initializable, Auth, IComponentRegistry {
     function _setDistributor(IDistributor val) private {
         require(address(val) != address(0), "invalid Distributor address");
         emit DistributorSet(distributor, val);
+        isComponent[address(val)] = true;
         distributor = val;
     }
 
@@ -83,6 +89,7 @@ abstract contract ComponentRegistry is Initializable, Auth, IComponentRegistry {
     function _setRSRTrader(IRevenueTrader val) private {
         require(address(val) != address(0), "invalid RSRTrader address");
         emit RSRTraderSet(rsrTrader, val);
+        isComponent[address(val)] = true;
         rsrTrader = val;
     }
 
@@ -91,6 +98,7 @@ abstract contract ComponentRegistry is Initializable, Auth, IComponentRegistry {
     function _setRTokenTrader(IRevenueTrader val) private {
         require(address(val) != address(0), "invalid RTokenTrader address");
         emit RTokenTraderSet(rTokenTrader, val);
+        isComponent[address(val)] = true;
         rTokenTrader = val;
     }
 
@@ -99,6 +107,7 @@ abstract contract ComponentRegistry is Initializable, Auth, IComponentRegistry {
     function _setFurnace(IFurnace val) private {
         require(address(val) != address(0), "invalid Furnace address");
         emit FurnaceSet(furnace, val);
+        isComponent[address(val)] = true;
         furnace = val;
     }
 
@@ -107,13 +116,35 @@ abstract contract ComponentRegistry is Initializable, Auth, IComponentRegistry {
     function _setBroker(IBroker val) private {
         require(address(val) != address(0), "invalid Broker address");
         emit BrokerSet(broker, val);
+        isComponent[address(val)] = true;
         broker = val;
     }
 
+    // 4.1.0 - Required for global lock
+    mapping(address => bool) public isComponent;
+
+    modifier onlyComponent() {
+        require(isComponent[_msgSender()], "not a component");
+        _;
+    }
+
+    function cacheComponents() external {
+        isComponent[address(rToken)] = true;
+        isComponent[address(stRSR)] = true;
+        isComponent[address(assetRegistry)] = true;
+        isComponent[address(basketHandler)] = true;
+        isComponent[address(backingManager)] = true;
+        isComponent[address(distributor)] = true;
+        isComponent[address(rsrTrader)] = true;
+        isComponent[address(rTokenTrader)] = true;
+        isComponent[address(furnace)] = true;
+        isComponent[address(broker)] = true;
+    }
+
     /**
      * @dev This empty reserved space is put in place to allow future versions to add new
      * variables without shifting down storage in the inheritance chain.
      * See https://docs.openzeppelin.com/contracts/4.x/upgradeable#storage_gaps
      */
-    uint256[40] private __gap;
+    uint256[39] private __gap;
 }
diff --git a/contracts/p1/Main.sol b/contracts/p1/Main.sol
index 418a55d6b..14a2a542d 100644
--- a/contracts/p1/Main.sol
+++ b/contracts/p1/Main.sol
@@ -161,11 +161,11 @@ contract MainP1 is
 
     // === Control Flow ===
 
-    function beginTx() external virtual {
+    function beginTx() external virtual onlyComponent {
         _nonReentrantBefore();
     }
 
-    function endTx() external virtual {
+    function endTx() external virtual onlyComponent {
         _nonReentrantAfter();
     }
 
diff --git a/test/Main.test.ts b/test/Main.test.ts
index 3405da86a..49ff65dff 100644
--- a/test/Main.test.ts
+++ b/test/Main.test.ts
@@ -259,6 +259,18 @@ describe(`MainP${IMPLEMENTATION} contract`, () => {
       expect(await main.rsrTrader()).to.equal(rsrTrader.address)
       expect(await main.rTokenTrader()).to.equal(rTokenTrader.address)
 
+      // Components registered
+      expect(await main.isComponent(rToken.address)).to.equal(true)
+      expect(await main.isComponent(stRSR.address)).to.equal(true)
+      expect(await main.isComponent(assetRegistry.address)).to.equal(true)
+      expect(await main.isComponent(basketHandler.address)).to.equal(true)
+      expect(await main.isComponent(backingManager.address)).to.equal(true)
+      expect(await main.isComponent(distributor.address)).to.equal(true)
+      expect(await main.isComponent(rsrTrader.address)).to.equal(true)
+      expect(await main.isComponent(rTokenTrader.address)).to.equal(true)
+      expect(await main.isComponent(furnace.address)).to.equal(true)
+      expect(await main.isComponent(broker.address)).to.equal(true)
+
       // Configuration
       const [rTokenTotal, rsrTotal] = await distributor.totals()
       expect(rTokenTotal).to.equal(bn(4000))
@@ -3998,6 +4010,50 @@ describe(`MainP${IMPLEMENTATION} contract`, () => {
         ).to.be.revertedWithCustomError(main, 'ReentrancyGuardReentrantCall')
       }
     })
+
+    it('Should allow to cache components', async () => {
+      await (await ethers.getContractAt('MainP1', main.address)).cacheComponents()
+
+      expect(await main.isComponent(rToken.address)).to.equal(true)
+      expect(await main.isComponent(stRSR.address)).to.equal(true)
+      expect(await main.isComponent(assetRegistry.address)).to.equal(true)
+      expect(await main.isComponent(basketHandler.address)).to.equal(true)
+      expect(await main.isComponent(backingManager.address)).to.equal(true)
+      expect(await main.isComponent(distributor.address)).to.equal(true)
+      expect(await main.isComponent(rsrTrader.address)).to.equal(true)
+      expect(await main.isComponent(rTokenTrader.address)).to.equal(true)
+      expect(await main.isComponent(furnace.address)).to.equal(true)
+      expect(await main.isComponent(broker.address)).to.equal(true)
+    })
+
+    it('Should only allow components to begin-end txs', async () => {
+      await expect(main.connect(owner).beginTx()).to.be.revertedWith('not a component')
+      await expect(main.connect(owner).endTx()).to.be.revertedWith('not a component')
+      await expect(main.connect(other).beginTx()).to.be.revertedWith('not a component')
+      await expect(main.connect(other).endTx()).to.be.revertedWith('not a component')
+
+      // Try with components
+      const components: Parameters<typeof main.init>[0] = {
+        rToken: rToken.address,
+        stRSR: stRSR.address,
+        assetRegistry: assetRegistry.address,
+        basketHandler: basketHandler.address,
+        backingManager: backingManager.address,
+        distributor: distributor.address,
+        rsrTrader: rsrTrader.address,
+        rTokenTrader: rTokenTrader.address,
+        furnace: furnace.address,
+        broker: broker.address,
+      }
+
+      // Loop through all components
+      for (const comp of Object.values(components)) {
+        await whileImpersonating(comp, async (compSigner) => {
+          await expect(main.connect(compSigner).beginTx()).to.not.be.reverted
+          await expect(main.connect(compSigner).endTx()).to.not.be.reverted
+        })
+      }
+    })
   })
 
   describeGas('Gas Reporting', () => {