Capping protein (CP), a heterodimer of alpha and beta subunits, is fou
nd in all eukaryotes. CP binds to the barbed ends of actin filaments i
n vitro and controls actin assembly and cell motility in vivo. Vertebr
ates have three alpha isoforms (alpha 1, alpha 2, alpha 3) produced fr
om different genes, whereas lower organisms have only one gene and one
isoform. We isolated genomic clones corresponding to the alpha subuni
ts of mouse CP and found three alpha 1 genes, two of which are pseudog
enes, and a single gene for both alpha 2 and alpha 3. Their chromosoma
l locations were identified by interspecies backcross mapping. The alp
ha 1 gene (Cappa1) mapped to Chromosome 3 between D3Mit11 and D3Mit13.
The alpha 1 pseudogenes (Cappa1-ps1 and Cappa2-ps2) mapped to Chromos
omes 1 and 9, respectively. The alpha 2 gene (Cappa2) mapped to Chromo
some 6 near Ptn. The alpha 3 gene (Cappa3) also mapped to Chromosome 6
, approximately 68 cM distal from Cappa2 near Kras2. One mouse mutatio
n, de, maps in the vicinity of the alpha 1 gene. No known mouse mutati
ons map to regions near the alpha 2 Or alpha 3 genes. (C) 1997 Academi
c Press.