A lobbying firm run by former Massachusetts Democratic Party Chairman Philip Johnston and a Braintree publishing company will move to the Heritage Landing office complex in North Quincy this year.

Johnston Assoc. leased 4,200 square feet and will relocate from 99 Summer St. in Boston in April. The firm provides public affairs consulting in the health care, education, transportation, insurance and real estate development sectors.

Galileo Press also leased 4,200 square feet beginning in September. The company, which specializes in scientific and academic publishing, will relocate from 100 Grossman Drive in Braintree.

Braintree-based developer Campanelli acquired the two-building, 358,000-square-foot Heritage Landing complex in June for $16.3 million. The property was 100-percent vacant after State Street Corp. vacated the space several years ago. Since Campanelli acquired the property, two other new tenants, Magellan Jets and Pharmalogics Recruiting, have leased 5,000 square feet and 8,500 square feet respectively. Campanelli is in the midst of a multi-million-dollar renovation project including new entrances, a café run by Sebastians of Boston, fitness center and conference center.