Catecholaminergic signaling regulates various physiological functions, such as blood pressure 1 and is implicated in drug dependence, affective disorders and male aggressive behavior 2,3 . The actions of released catecholamines are terminated by sodium-driven, high-affinity transporters in the plasma membrane of the releasing neurons 4,5 and by a corticosteronesensitive, low-affinity, high-capacity extraneuronal transport system 6 , originally named uptake 2 , found in sympathetically innervated tissues 7 and in central nervous system glia 8 . Here we report the molecular identification and pharmacological characterization of the extraneuronal catecholamine transporter, which is unrelated to the family of sodium-driven neuronal monoamine transporters 5 .Extraneuronal uptake is closely related to the non-neuronal metabolism of catecholamines 7 by catechol-O-methyltransferase (COMT), which exists almost exclusively in non-neuronal cells 9 , and monoamine oxidases (MAO-A and MAO-B). Extraneuronal transport is the predominant pathway for terminating the actions of circulating adrenaline and noradrenaline 10 . Although neuronal and extraneuronal uptake compete for released catecholamines, these transport systems have distinct pharmacological profiles, that is, affinity for substrates and sensitivity to various drugs. Overlap in the antagonist sensitivity between extraneuronal catecholamine uptake and apical renal transport of organic cations by OCT2 (ref. 11) raised the possibility that the extraneuronal transporter might belong to the recently defined family of amphiphilic solute facilitators (ASF) 12 . Degenerate oligonucleotides were derived from common sequence motifs of the ASF family and used for PCR on cDNA from Caki-1 cells, a human kidney carcinoma cell line known to express extraneuronal noradrenaline transport 13 . Amplicons of the expected sizes were isolated by ultraviolet-protected gel electrophoresis, cloned and sequenced. A fragment with similarity to members of the ASF family was identified. This fragment, in northern analysis of Caki-1 mRNA, detected a single band with a length of approximately 3.4 kb. The full-length cDNA of the corresponding transporter was assembled from a Caki-1 cDNA library clone and a fragment from inverse PCR. Because of its functional characteristics, we named this new transporter EMT (extraneuronal transporter for monoamine transmitters).Amino-acid sequence analysis identified EMT as a new member of the ASF transporter family 12 . No proteins highly homologous to EMT are yet known. EMT is similar to the OCT and OAT proteins (renal transporters for organic cations and organic anions), with identity (similarity) scores of about 50% (70%) and 32% (55%), respectively. EMT consists of 556 amino acids ( Fig. 1) with 12 putative transmembrane segments. To determine whether the functional properties of EMT match the characteristics of extraneuronal transport of catecholamines, the EMT cDNA was inserted into the expression vector pcDNA3 and transfected into 293 cells, a cell line fro...

Léri-Weill syndrome (LWS) or dyschondrosteosis represents a short stature syndrome characterised by the mesomelic shortening of the forearms and lower legs and by bilateral Madelung deformity of the wrists. Recently, mutations in the pseudoautosomal homeobox gene SHOX have been shown to be causative for this disorder. This gene has previously been described as the short stature gene implicated in Turner syndrome (TS). We studied 32 Léri-Weill patients from 18 different German and Dutch families and present clinical, radiological and molecular data. Phenotypic inter-and intrafamilial heterogeneity is a frequent finding in LWS, and phenotypic manifestations are generally more severe in females. In males, muscular hypertrophy is a frequent finding. To test for SHOX mutations we used FISH, Southern blot and SSCP analysis as well as long-range PCR and sequencing. We identified (sub)microscopic deletions encompassing the SHOX gene region in 10 out of 18 families investigated. Deletion sizes varied between 100 kb and 9 Mb and did not correlate with the severity of the phenotype. We did not detect SHOX mutations in almost half (41%) the LWS families studied, which suggests different genetic etiologies.

Deletion of the SHOX region on the human sex chromosomes has been shown to result in idiopathic short stature and proposed to play a role in the short stature associated with Turner syndrome. We have identified a human paired-related homeobox gene, SHOT, by virtue of its homology to the human SHOX and mouse OG-12 genes. Two different isoforms were isolated, SHOTa and SHOTb, which have identical homeodomains and share a C-terminal 14-amino acid residue motif characteristic for craniofacially expressed homeodomain proteins. Differences between SHOTa and b reside within the N termini and an alternatively spliced exon in the C termini. In situ hybridization of the mouse equivalent, OG-12, on sections from staged mouse embryos detected highly restricted transcripts in the developing sinus venosus (aorta), female genitalia, diencephalon, mes-and myelencephalon, nasal capsula, palate, eyelid, and in the limbs. SHOT was mapped to human chromosome 3q25-q26 and OG-12 within a syntenic region on chromosome 3. Based on the localization and expression pattern of its mouse homologue during embryonic development, SHOT represents a candidate for the Cornelia de Lange syndrome.

Accurate genetic and physical maps for the human pseudoautosomal region were constructed by use of sperm typing and high-resolution radiation-hybrid mapping. PCR analysis of 1,912 sperm was done with a manual, single-sperm isolation method. Data on four donors show highly significant linkage heterogeneity among individuals. The most significant difference was observed in a marker interval located in the middle of the Xp/Yp pseudoautosomal region, where one donor showed a particularly high recombination fraction. Longitudinal models were fitted to the data to test whether linkage heterogeneity among donors was significant for multiple intervals across the region. The results indicated that increased recombination in particular individuals and regions is compensated for by reduced recombination in neighboring intervals. To investigate correspondence between physical and genetic distances within the region, we constructed a high-resolution radiation-hybrid map containing 29 markers. The recombination fraction per unit of physical distance varies between regions ranging from 13- to 70-fold greater than the genome-average rate.