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Life science developer Alexandria Real Estate Equities is expanding its South Boston portfolio with the acquisition of two parcels near the Boston Convention and Exhibition Center spanning nearly 6 acres.

The $168.5 million transactions which closed this week include a self-storage facility at 380 E St. and the trucking terminal at 420 E St., according to Suffolk County deeds.

The sellers are 920 Storage, an affiliate of Stoughton-based Conroy Development, and E420 LLC of Boston. The 380 E St. site contains a 105,272-square-foot storage facility completed in 2013. The 420 E St. property is occupied by a 88,256-square-foot terminal built in 1983, according to public records.

Pasadena, California-based Alexandria recently has concentrated on South Boston and the Seaport District for growth of its 8.6 million-square-foot Greater Boston portfolio, which generates 36 percent of the REIT’s annual rental revenues.

Alexandria and Newton-based National Development are partnering on development of a 316,750-square-foot office-lab building at 15 Necco St. in Fort Point, which received approval from the Boston Planning and Development Authority in September. It’s also seeking approval for a 210,000-square-foot office-lab building at 99 A St., a proposal that has been scaled back in size twice after community objections.