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The progesterone receptor gene (PGR), the gene coding for porphobilinogen deaminase (PBGD), the gene coding for a neural cell adhesion molecule (NCAM), the oncogene ETS1, and the anonymous genomic sequence D11S29 have been previously located on the long arm of chromosome 11. However, gene localizations obtained with different gene-mapping procedures have led to occasional discrepancies. To localize these genes more precisely, we hybridized five human DNA sequences with different chromosomal rearrangements, including four balanced and one unbalanced translocations. We show here that the order of these five sequences is cen PGR-PBGD-D1 lS29/NCAM/ETSl-tel.

U3 small nucleolar RNA, which is believed to play a role in eukaryotic rRNA processing, is encoded by a small family of genes (5–10 copies/haploid genome) in mammals. In mouse, functional genes encoding the major U3B RNA form have been isolated, with all copies identified so far having evolved in a tightly concerted fashion. However, knowledge of the precise number and relative localization of all gene-family members has been hampered by the presence of multiple copies of U3B-processed pseudogenes in the mouse genome. In this study, we took advantage of a probe that is specific for functional U3B genes to address this question, using both Southern hybridization of genomic DNA and in situ hybridization of metaphase chromosomes. We show that the mouse haploid genome contains four functional U3B genes, all of which are clustered in a single chromosomal locus. They map to the C-D bands of mouse chromosome 11, within one of the most extended segments of gene-linkage conservation known between the mouse and human genomes, corresponding to a major portion of human chromosome 17. By contrast, the multiple (nonfunctional) U3 retrogenes are dispersed over several mouse chromosomes.

The genes encoding calbindin D28k (CALB1) and calretinin (CALB2), two closely related calcium-binding proteins, were mapped by in situ hybridization to the 8q21.3→ q22.1 and 16q22→q23 regions of the human genome, respectively. These localizations match the chromosomal regions where the carbonic anhydrase isozyme gene cluster (CA1 CA2, CA3) and the related gene CA7 have been described, respectively. This suggests a common duplication·the calbindin/calretinin and the carbonic anhydrase ancestral genes.

The gene for human calcyphosine (CAPS) was assigned to the pl3.3 region of chromosome 19 by in situ hybridization.

The gene for human thyrotropin receptor (TSHR) was assigned to chromosome J4, band q31, by in situ hybridization, using a probe for TSHR