A proposal to spin off Entergy’s electric transmission business to improve efficiency of its service in Mississippi is before the Public Service Commission.

If approved, the multistate utility’s approximately 15,800 miles of interconnected transmission lines and substations in Mississippi, Louisiana, Arkansas and Texas will be sold to a subsidiary of Michigan-based ITC Holdings Corp., the nation’s largest independent electric transmission company.

The move is part of similar regulatory filings before state and federal regulators and to bring Entergy subsidiaries into the Midwest Independent System Operator, a regional transmission network of multiple utilities in which ITC operates.

“This proposal builds on years of hard work and aggressive investment to improve service to our customers,” Haley Fisackerly, Entergy Mississippi president and CEO, said in a statement. “It paves the way for new investment, new expertise and an independent company singularly focused on transmission in the region.”

The two entities expect to close the deal in 2013 pending regulatory approvals in Mississippi, Arkansas, Texas and Missouri. The Louisiana Public Service Commission OK’d the request earlier this year. In September, when the request was filed with the Arkansas PSC, ITC indicated the transaction was conditional upon Entergy receiving all regulatory approvals to join MISO.

Joining MISO would enable the utility to track energy costs in real time and flow the cheapest energy wherever it’s needed within the system, officials with the network said in July.

About 750 Entergy employees, including key supervisors in its transmission business, will become employees of ITC if the request is approved, with its headquarters in Jackson, according to a news release from the utility. Further hearing dates are to be scheduled.

Entergy serves 437,000 customers in 45 Mississippi counties and 2.8 million customers in its four-state footprint.

ITC and its subsidiaries in the Midwest own and operate high-voltage transmission lines and facilities in Michigan, Iowa, Minnesota, Illinois, Missouri, Kansas and Oklahoma.