A Grantor Irrevocable Trust is a separate entity with its own tax ID number (EIN).
The GIT can hold any type of assets from checking accounts, stock brokerage accounts, real estate, annuities and insurance products.
A GIT is required to file its own tax return if it has income greater than $10.00 per year. Since most tax preparers charge a minimum of $500 to file a Trust return (many times a lot more) the GIT would be better earning no interest or placing the GIT assets into tax deferred investments.
You should consult your tax professional regarding all tax questions.