Synaptotagmin genes on mouse chromosomes 1, 7, and 10 and human chromosome 19

Human synaptotagmin V (SYT5): sequence, genomic structure, and chromosomal location

We have determined the sequence, genomic structure, and chromosomal location of the human synaptotagmin V (SYTV) gene. The human SYTV gene encodes a 386-amino-acid product which is 91% identical to rat Syt V. The human SYTV open reading frame is interrupted by seven introns which can be alternatively spliced. Human SYTV was found to lie very close to SYTIII on chromosome 19q13.4 by PCR analysis of somatic cell hybrid DNA and by DNA hybridization to arrayed cosmids of the chromosome 19 metric physical map. This provides the first report of linked synaptotagmin genes.

Insertional mutation of the motor endplate disease (med) locus on mouse chromosome 15

Homozygous transgenic mice from line A4 have an early-onset progressive neuromuscular disorder characterized by paralysis of the rear limbs, muscle atrophy, and lethality by 4 weeks of age. The transgene insertion site was mapped to distal chromosome 15 close to the locus motor endplate disease (med). The sequence of mouse DNA flanking the insertion site junctions was determined. A small (< 20 kb) deletion was detected at the insertion site, with no evidence of additional rearrangement of the chromosomal DNA. Noncomplementation of the transgene-induced mutation and med was demonstrated in a cross with medJ/+mice. The new allele is designated medTgNA4Bs (medtg). The homologous human locus MED was assigned to chromosome 12. Synaptotagmin 1 and contactin 1 were eliminated as candidate genes for the med mutation. The transgene-induced allele provides molecular access to the med gene, whose function is required for synaptic transmission at the neuromuscular junction and long-term survival of cerebellar Purkinje cells.