allantoin assimilation pathway

The pathways by which allantoin is processed and converted to ureidoglycolate, and then into metabolically useful substrates. E. coli are able to utilize allantoin as a sole nitrogen source under anaerobic conditions by converting it to ureidoglycolate; this may be further metabolized to produce glyoxylate and thence 3-phosphoglycerate, or alternatively oxidized to oxolureate, which can converted into oxamate and carbamoylphosphate. This may then be further metabolized to CO2, NH4+ and ATP.

RNA polymerase I general transcription initiation factor activity

A general transcription initiation factor activity that contributes to transcription start site selection and transcription initiation of genes transcribed by RNA polymerase I. Factors required for RNA polymerase I transcription initiation include upstream activation factor (UAF), core factor (CF), TATA binding protein (TBP) and RRN3. In all species characterized, RNA polymerase I transcribes a large polycistronic transcript that is processed into several mature rRNAs (3 or 4 depending on the species), including the large subunit rRNA (28S in humans), the small subunit rRNA (18S in humans), as well as one or two additional smaller rRNAs (the 5.8S rRNA in humans). In most species, this large rRNA transcript is the sole product of RNA polymerase I. However there are rare exceptions, such as Trypanosoma brucei, where RNA polymerase I also transcribes certain mRNAs.