title: Polymorphism in the exon 4 of β-lactoglobulin variant B precursor gene and its association with milk traits and protein structure in Chinese Holstein.
abstract: β-lactoglobulin (β-LG) is the major whey protein in the milk. In order to investigate the polymorphism of β-LG variant B precursor (β-LG B*: GenBank accession no. DQ489319) gene and its effects on the milk traits, the single-strand conformation polymorphism method (PCR-SSCP) were adopted to analyze polymorphism between 5229th and 5476th bp in the β-LG B* gene in Chinese Holstein. Four genotypes were found (AA, AB, AC and ABC) and 3 single nucleotide polymorphisms (SNPs) were detected (g.5239C>A, g.5240A>C, g.5305C>T and mix type g.5305C/T) in the exon 4 of β-LG B* gene. It was also found that the protein contents of AB, AC and ABC dairy cows were higher than AA (P < 0.05), and AC cows were the highest among them. Three SNPs (g.5239C>A, g.5240A>C and g.5305C>T) might affect the milk trait and all of them were high polymorphism (0.5 < PIC < 1.0). In further researches, the three SNPs also caused amino acid change (Asp>Glu, Thr>Pro and Ala>Val) respectively, and the spatial secondary and tertiary structure forecasting result also showed that single amino acid change influence protein spatial structure change in Chinese Holstein. Taken together, it is suggested that these SNPs change β-LG B* gene structure and expression. The polymorphism possibly holds the secret of milk protein and fat contents in the milk of Chinese Holstein.
authors.affiliation: College of Life Sciences, Anhui Normal University, Key Laboratory of Biotic Environment and Ecological Safety in Anhui Province, Wuhu, 241000, Anhui, China.
authors.forename: Fan
authors.initials: F
authors.lastname: Yang
authors.forename: Lian
authors.initials: L
authors.lastname: Li
authors.forename: Huiling
authors.initials: H
authors.lastname: Liu
authors.forename: Yafei
authors.initials: Y
authors.lastname: Cai
authors.forename: Genlin
authors.initials: G
authors.lastname: Wang
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002417:Cattle / Q000235:genetics*; D002681:China; D004587:Electrophoresis, Agar Gel; D005091:Exons / Q000235:genetics*; D005260:Female; D056726:Genetic Association Studies; D056426:Genetic Loci / Q000235:genetics; D005838:Genotype; D007438:Introns / Q000235:genetics; D007782:Lactoglobulins / Q000737:chemistry / Q000235:genetics*; D008894:Milk Proteins / Q000737:chemistry* / Q000235:genetics; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*; D011498:Protein Precursors / Q000737:chemistry / Q000235:genetics*; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D019655:Quantitative Trait, Heritable; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D012984:Software
chemical_list: D007782:Lactoglobulins; D008894:Milk Proteins; D011498:Protein Precursors