The transcription factor IIIC (TFIIIC) is a multisubunit DNA-binding factor required for promoter recognition and TFIIIB assembly on tRNA genes transcribed by RNA polymerase III. Yeast TFMC consists of six subunits, organized in the two globular subcomplexes, tau A and tau B, which recognize two internal tDNA promoter elements, the A and the B block, respectively. As a first step toward a detailed structural analysis of TFIIIC, we report here the expression, proteolytic analysis, reconstitution, and crystallization of the complex between yeast TFIIIC subunits tau 91 and tau 60. Proteolysis provided an insight into the domain structure of tau 160 and tau 91. Both the proteins form a stable complex that does not require an N-terminal, protease-sensitive extension of tau 91. Crystals diffracting beyond 3.2 angstrom were obtained from a complex formed by full-length tau 60 and the N-terminally truncated form of tau 91 lacking this extension. (c) 2005 Elsevier Inc. All rights reserved.