Two phage clones containing SHMT-ps1 have been mapped by fluorescence in situ hybridisation to 1p32.3-33.     ///    The complete SHMT-ps1 sequence of 2538 nt is bounded by two 16 nt direct repeats that are characteristic of retroelement insertion sites.     ///    We have isolated phage clones containing human genomic sequences homologous to cytosolic SHMT and have found these to contain a processed pseudogene (SHMT-ps1) with a 90% identity to cloned SHMT cDNAs.     ///    SHMT-ps1 contains 2335 nt that are homologous to SHMT but it has an additional leader sequence of 203 nt of unknown origin. 