The enzymes which catalyze the reversible phosphorolysis of pyrimidine nucleosides are involved in the degradation of these compounds and in their utilization as carbon and energy sources, or in the rescue of pyrimidine bases for nucleotide synthesis. phosphate + thymidine = 2-deoxy-alpha-D-ribose 1-phosphate + thymine Pyrimidine metabolism; dTMP biosynthesis via salvage pathway; dTMP from thymine: step 1/2. Homodimer. Belongs to the thymidine/pyrimidine-nucleoside phosphorylase family.