In this paper, we have developed a novel unified approach to deal with arbitrary transmitted power constraints for designing jointly the MMSE precoders and decoders in uplink multiuser MIMO systems. This work is an extension of the first iterative approach developed by Serbetli and Yener (5) for per-user power constraint. An explicit expression relating Lagrange multipliers with the per-user constraint can be obtained using the proposed approach to mitigate the time consuming root searching for the Lagrange multipliers in (5). Moreover, the explicit expression allows the MMSE solution subject to arbitrary transmit power constraints including the practical per-antenna power and peak power constraints. It is shown in some two-user numerical examples that the raw BER performance obtained from per- antenna power constraint is similar to that of the per-user power constraint and is 1-2.5 dB better than that of the peak power constraint.