We report the cloning and characterization of the alternatively spliced mouse gene zfp162, formerly termed mzfm, the homolog of the human ZFM1 gene encoding the splicing factor SF1 and a putative signal transduction and activation of RNA (STAR) protein. The zfp162 gene is about 14 kb long and consists of 14 exons and 13 introns. Comparison of zfp162 with the genomic sequences of ZFM1/SF1 revealed that the exon-intron structure and exon sequences are well conserved between the genes, whereas the introns differ in length and sequence composition. Using fluorescent in situ hybridization, the zfp162 gene was assigned to chromosome 19, region B. Screening of a genomic library integrated in lambda DASH II resulted in the identification of the 5'-flanking region of zfp162. Sequence analysis of this region showed that zfp162 is a TATA-less gene containing an initiator control element and two CCAAT boxes. The promoter exhibits the following motifs: AP-2, CRE, Ets, GRE, HNF5, MRE, SP-1, TRE, TCF1, and PU.1. The core promoter, from position -331 to -157, contains the motifs CRE, SP-1, MRE, and AP-2, as determined in transfected CHO-K1 cells and IC-21 cells by reporter gene assay using a secreted form of human placental alkaline phosphatase. The occurrence of PU.1/GRE supports the view that the zfp162 gene encodes a protein involved not only in nuclear RNA metabolism, as the human ZFM1/SF1, but also in as yet unknown macrophage-inherent functions.