Submitted to: Animal Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/23/2001
Publication Date: 2/1/2002
Interpretive Summary: In an attempt to identify the gene on pig chromosome 4 which is responsible for QTL affecting growth and carcass length, we mapped a candidate gene named endoplasmic reticulum-resident type II transmembrane glycosyltransferase (EXT1). This gene has been shown to affect differentiation and growth of cells and was expected to map to chromosome 4 in the pig. EXT1 mapped to chromosome 4 position 41 cM in the MARC genetic map. While this gene did map to the targeted chromosome, its location on the chromosome excludes it from further consideration as a candidate gene for the identified growth and carcass length QTL.
Technical Abstract: The endoplasmic reticulum-resident type II transmembrane glycosyltransferase (EXT1) was mapped in the porcine genome. This gene is involved in the chain elongation step of heparin sulphate biosynthesis, which is needed for cell surface proteoglycan synthesis. Cell surface proteoglycans play a crucial role in morphogenesis, growth regulation and tumor suppression. A biallelic polymorphism was found with HaeIII, which cuts the PCR amplicon into several fragments. Allele A, in which the polymorphic restriction site is absent, is characterised by the presence of a 1.0 kb fragment, while allele B possesses fragments of 0.9 kb and 0.1 kb. Multiple-point linkage analysis was performed in USDA-MARC backcross pedigree. On the basis of 52 informative meioses the EXT1 gene has been located on the USDA-MARC linkage map to SSC4 at position 41 Kosambi cM at the same position as microsatellites SWR73, SWR2179 and SW2409. Due to EXT1's map position this gene can be excluded as a candidate gene for QTLs on chromosome 4 affecting growth or carcass length.