diff --git a/src/mol-state/object.ts b/src/mol-state/object.ts
index e8bdf73751d8d4b7fe63d5cffb7c6a834ba4204a..857d3249f5ea0cda44ad9f39f4d1cbf63e014d53 100644
--- a/src/mol-state/object.ts
+++ b/src/mol-state/object.ts
@@ -59,7 +59,6 @@ interface StateObjectCell<T = StateObject> {
     // Which object was used as a parent to create data in this cell
     sourceRef: Transform.Ref | undefined,
 
-    version: string
     status: StateObjectCell.Status,
 
     params: {
diff --git a/src/mol-state/state.ts b/src/mol-state/state.ts
index 42030da32278c8e08da5aefae600c17bf1d455ea..766daa3fb470882e8c853923eb25567fa2f9ce6f 100644
--- a/src/mol-state/state.ts
+++ b/src/mol-state/state.ts
@@ -8,7 +8,6 @@ import { StateObject, StateObjectCell } from './object';
 import { StateTree } from './tree';
 import { Transform } from './transform';
 import { Transformer } from './transformer';
-import { UUID } from 'mol-util';
 import { RuntimeContext, Task } from 'mol-task';
 import { StateSelection } from './state/selection';
 import { RxEventHelper } from 'mol-util/rx-event-helper';
@@ -184,7 +183,6 @@ class State {
             sourceRef: void 0,
             obj: rootObject,
             status: 'ok',
-            version: root.version,
             errorText: void 0,
             params: {
                 definition: {},
@@ -350,7 +348,7 @@ function findUpdateRoots(cells: Map<Transform.Ref, StateObjectCell>, tree: State
 
 function findUpdateRootsVisitor(n: Transform, _: any, s: { roots: Ref[], cells: Map<Ref, StateObjectCell> }) {
     const cell = s.cells.get(n.ref);
-    if (!cell || cell.version !== n.version || cell.status === 'error') {
+    if (!cell || cell.transform.version !== n.version || cell.status === 'error') {
         s.roots.push(n.ref);
         return false;
     }
@@ -406,7 +404,6 @@ function initCellsVisitor(transform: Transform, _: any, { ctx, added }: InitCell
         transform,
         sourceRef: void 0,
         status: 'pending',
-        version: UUID.create22(),
         errorText: void 0,
         params: void 0
     };
@@ -556,7 +553,6 @@ async function updateNode(ctx: UpdateContext, currentRef: Ref): Promise<UpdateNo
 
     // special case for Root
     if (current.transform.ref === Transform.RootRef) {
-        current.version = transform.version;
         return { action: 'none' };
     }
 
@@ -574,7 +570,6 @@ async function updateNode(ctx: UpdateContext, currentRef: Ref): Promise<UpdateNo
         current.params = params;
         const obj = await createObject(ctx, currentRef, transform.transformer, parent, params.values);
         current.obj = obj;
-        current.version = transform.version;
 
         return { ref: currentRef, action: 'created', obj };
     } else {
@@ -591,14 +586,11 @@ async function updateNode(ctx: UpdateContext, currentRef: Ref): Promise<UpdateNo
                 const oldObj = current.obj;
                 const newObj = await createObject(ctx, currentRef, transform.transformer, parent, newParams);
                 current.obj = newObj;
-                current.version = transform.version;
                 return { ref: currentRef, action: 'replaced', oldObj, obj: newObj };
             }
             case Transformer.UpdateResult.Updated:
-                current.version = transform.version;
                 return { ref: currentRef, action: 'updated', obj: current.obj! };
             default:
-                current.version = transform.version;
                 return { action: 'none' };
         }
     }
diff --git a/src/mol-state/state/selection.ts b/src/mol-state/state/selection.ts
index 828f7c9cf85a0926dae10d13bc6c675094939b64..d9aec37f87f11cff889c322832dd020e0c3b16dc 100644
--- a/src/mol-state/state/selection.ts
+++ b/src/mol-state/state/selection.ts
@@ -29,7 +29,7 @@ namespace StateSelection {
     }
 
     function isObj(arg: any): arg is StateObjectCell {
-        return (arg as StateObjectCell).version !== void 0 && (arg as StateObjectCell).transform !== void 0;
+        return (arg as StateObjectCell).transform !== void 0 && (arg as StateObjectCell).status !== void 0;
     }
 
     function isBuilder(arg: any): arg is Builder {