TransCanada has already offered its MLP two such opportunities. First, it has proposed to sell its 49.3% interest in the Iroquois Gas Transmission System, which it owns as part of a joint venture with Dominion Resources ( D -0.08% ). In addition, TransCanada has offered its remaining 11.8% interest in the Portland Gas Transmission System to its MLP. TC Pipelines already owns a 49.9% stake in that system, which it acquired from its parent last year for $223 million. TransCanada hasn't disclosed the terms of either of its latest sales so it's unclear how much cash it might receive from these two transactions.