CDR managing director Patrick Donovan and director Sarah Gestetner are leading the account and report to GI director Phil Kaziewicz.
GI does not retain CDR for financial communications but used the firm when the venture capital organisation backed a senior management buyout of healthcare company NHP in March.
Yates is using Financial Dynamics, its retained financial PR adviser of the last two and a half years. FD London chief operating officer Tim Spratt runs the account.
The company is also using Close Brothers Corporate Finance for financial advice on the offer. Yates chief executive Mark Jones is leading the bid for the 150-strong bar group, which this week was due to announce in its preliminary results that it recommended the cash offer of 140 pence per share.
The Yates family has not been represented on the company's board of directors since the departure of chief executive Peter Yates 18 months ago, but the family retains ownership of around 30 per cent of the business.
GI's financial backing of a successful management buyout would put the bar group in a good position to benefit from the likely consolidation of the high-street pub sector.
GI was set up in 2001 with $526m (£286m) in capital. The US group is backed by Calpers, the world's largest public pensions fund.
Yates announced in its March pre-close of trading statement that group like-for-like sales for the ten weeks to 14 March were up 2.6 per cent, with 21st Century Yates bars showing an increase of 5.3 per cent.
Sales for the 50-week period to 14 March fell 2.8 per cent, with Yates's brand sales down 3.9 per cent. However, the Ha!Ha! chain increased sales by 3.7 per cent.