Adjustable vehicle seat, and vehicle equipped with such an adjustable seat

An adjustable seat (1) for a vehicle (2) has a seat portion (8) and a backrest (7), and is movable between a first operating configuration, in which the seat portion (8) and the backrest (7) define accommodation for at least one passenger, and a second operating configuration, in which the seat portion (8) defines the front of a rear loading compartment (10) of the vehicle (2), and the backrest (7) defines the top of the loading compartment (10).