diff --git a/src/mol-model-props/computed/membrane.ts b/src/mol-model-props/computed/membrane.ts
index 8053b526154b5b767ecfb283e7227512df7e443a..e87baefa11736cf2737693246caa48001bde4136 100644
--- a/src/mol-model-props/computed/membrane.ts
+++ b/src/mol-model-props/computed/membrane.ts
@@ -10,12 +10,20 @@ import { Structure } from '../../mol-model/structure';
 import { CustomStructureProperty } from '../common/custom-structure-property';
 import { CustomProperty } from '../common/custom-property';
 import { CustomPropertyDescriptor } from '../../mol-model/custom-property';
-import { ANVILParams, Membrane } from './membrane/ANVIL';
+import { ANVILParams, Membrane, ANVILProps } from './membrane/ANVIL';
 import { AccessibleSurfaceAreaProvider } from './accessible-surface-area';
 
-export const MembraneParams = {
-    ...ANVILParams
-};
+function getMembraneParams(data?: Structure) {
+    let defaultType = 'anvil' as 'anvil' | 'opm'; // TODO flip - OPM should be default if PDB identifier is known
+    return {
+        type: PD.MappedStatic(defaultType, {
+            'opm': PD.EmptyGroup({ label: 'OPM' }),
+            'anvil': PD.Group(ANVILParams, { label: 'ANVIL' })
+        }, { options: [['opm', 'OPM'], ['anvil', 'ANVIL']] })
+    };
+}
+
+export const MembraneParams = getMembraneParams();
 export type MembraneParams = typeof MembraneParams
 export type MembraneProps = PD.Values<MembraneParams>
 
@@ -29,11 +37,21 @@ export const MembraneProvider: CustomStructureProperty.Provider<MembraneParams,
     defaultParams: MembraneParams,
     getParams: (data: Structure) => MembraneParams,
     isApplicable: (data: Structure) => true,
-    // TODO needs ASA to be computed (or 'resolved' before trying computing topology) - how to achieve?
-    // TODO potentially, this could behave like secondary structure info where data can be either parsed or computed
     obtain: async (ctx: CustomProperty.Context, data: Structure, props: Partial<MembraneProps>) => {
-        await AccessibleSurfaceAreaProvider.attach(ctx, data);
         const p = { ...PD.getDefaultValues(MembraneParams), ...props };
-        return { value: await Membrane.compute(data, p).runInContext(ctx.runtime) };
+        switch (p.type.name) {
+            case 'anvil': return { value: await computeAnvil(ctx, data, p.type.params) };
+            case 'opm': return { value: await computeOpm(data) };
+        }
     }
-});
\ No newline at end of file
+});
+
+async function computeAnvil(ctx: CustomProperty.Context, data: Structure, props: ANVILProps): Promise<Membrane> {
+    await AccessibleSurfaceAreaProvider.attach(ctx, data);
+    const p = { ...PD.getDefaultValues(MembraneParams), ...props };
+    return await Membrane.compute(data, p).runInContext(ctx.runtime);
+}
+
+async function computeOpm(structure: Structure): Promise<Membrane> {
+    throw Error('TODO impl');
+}
\ No newline at end of file