Issuer Risk Member Issuer Risk Member MLP Risk Member MLP Risk Member MainGate MLP Fund MainGate MLP Fund Series S000031058 MainGate MLP Fund Class C MainGate MLP Fund Class C C000142071 MLCPX Alerian MLP Total Return Index (Class A&I) (reflects no deduction for fees, expenses or taxes) Alerian MLP Total Return Index (Class A&I) (reflects no deduction for fees, expenses or taxes) Market Risk Member Market Risk Member Alerian MLP Total Return Index (Class C) (reflects no deduction for fees, expenses or taxes) Alerian MLP Total Return Index (Class C) (reflects no deduction for fees, expenses or taxes) S&P 500 Index (Class A&I) (reflects no deduction for fees, expenses or taxes) S&P 500 Index (Class A&I) (reflects no deduction for fees, expenses or taxes) MainGate MLP Fund Class I MainGate MLP Fund Class I C000096313 IMLPX Foreign Securities Risks Member Foreign Securities Risks Member S&P 500 Index (Class C) (reflects no deduction for fees, expenses or taxes) S&P 500 Index (Class C) (reflects no deduction for fees, expenses or taxes) Deferred Tax Assets And Liabilities Risk; Potential NAV Decline Risk Member Deferred Tax Assets And Liabilities Risk; Potential NAV Decline Risk Member Fund Tax Risks Member Fund Tax Risks Member Concentration Risk Member Concentration Risk Member MainGate MLP Fund Class A MainGate MLP Fund Class A C000096312 AMLPX Management Risk Member Management Risk Member Commodities Risk Member Commodities Risk Member Liquidity Risk Member Liquidity Risk Member MLP Tax Risks Member MLP Tax Risks Member Energy Sector Risk Member Energy Sector Risk Member Small- And Mid-Cap Risk Member Small- And Mid-Cap Risk Member Strategy Risk Member Strategy Risk Member