Passenger transport vehicle seat and vehicle comprising such a seat

A passenger transport vehicle seat (2, 2') comprises a support element (4, 6) intended to receive, by bearing, at least one portion of a user's body, and a support structure (8) for the support element (4, 6), said support element (4, 6) comprising a fastening portion (16, 20) for fixing to the support structure (8). The support structure (8) comprises a longitudinal neck (38) for receiving said fixing portion (16, 20), a longitudinal beam (26), mobile in a transverse direction relative to the neck (38) between a locking position in which the fixing portion (16, 20) is locked in a vise between the neck (38) and the beam (26) and a disassembled position in which the fixing portion (16, 20) is mobile relative to the neck (38) and the beam (26), and means (28, 28') for translating the beam (26) relative to the neck (38) between the locking position and the disassembled position.