This paper investigates reconfigurable pixel antenna (RPA)-based electronic movable antennas (REMAs) for multiuser communications. First, we model each REMA as an antenna with a set of predefined and discrete selectable radiation positions within the radiating region. Considering the trade-off between performance and cost, we propose partially-connected and fully-connected RPA-based electronic movable-antenna arrays (PC/FC-REMAA). Then, we formulate a multiuser sum-rate maximization problem subject to the power and hardware constraints of the PC/FC-REMAA. To solve this problem, we propose a two-step multiuser beamforming and antenna selection scheme. In addition, we revisit mechanical movable antennas (MMAs) to establish a benchmark for evaluating the performance of REMA-enabled multiuser communications. Finally, we analyze the performance gap between REMAs and MMAs. Based on Fourier analysis, we derive the maximum power loss of REMAs compared to MMAs for any given position interval. Specifically, we show that REMAs lose at most 3.25% power relative to MMAs when the position interval is one-tenth of the wavelength. Simulation results demonstrate the effectiveness of the proposed methods.