(Reuters) - U.S. auto parts maker Johnson Controls Inc (>> Johnson Controls Inc) reported lower-than-expected first-quarter revenue, largely because of lower sales in its automotive seating and interiors business.

Revenue fell to $8.93 billion in the quarter through Dec. 31 from $9.62 billion a year ago, missing analysts' forecasts for $9.29 billion. Net income dropped to $490 million, down 5 percent from a year earlier.

Excluding items, the company earned 82 cents a share, as analysts expected.

The company said it expects a second-quarter profit of 80-83 cents a share and full-year profit of $3.70-$3.90.

Sales in its automotive unit, which makes car seats and interiors for companies such as Toyota Motor Corp (>> Toyota Motor Corp) and General Motors Co (>> General Motors Company), fell 19.9 percent to $4.23 billion in the first quarter, from a year earlier.

The automotive unit accounted for 47 percent of the company's sales in the quarter, compared with 55 percent a year ago.

Johnson Controls, which agreed to buy Ireland-based Tyco International Plc (>> Tyco International PLC) on Monday, has been preparing to spin off its automotive seating and interiors operations, and refocus on buildings, fire security and batteries.

The company said the spinoff of the automotive business - named Adient - was on track for October 2016.

The automotive unit revenue fell primarily due to "the deconsolidation of the interiors business," including the formation of an interiors joint venture in July 2015 with China's Yanfeng Automotive Trim Systems, the company said.

Net income attributable to Johnson Controls fell to $450 million, or 69 cents per share, in the quarter ended Dec. 31, from $507 million, or 76 cents per share.

Shares were down slightly in premarket trading at $35.13.

(Reporting by Radhika Rukmangadhan in Bengaluru and Paul Lienert in Detroit; Editing by Bernadette Baum)