The synthesis of alpha-2,3-linked sialic acid to Gal(beta-1,3)GalNAc is mediated by at least 3 beta-galactoside alpha-2,3-sialyltransferases, SiaT-4, that are encoded by 3 distinct genes. In contrast, only a single gene encodes the beta-galactoside alpha-2,6-sialyltransferase, SiaT-1.
NCBI Summary:
The protein encoded by this gene is a type II membrane protein that catalyzes the transfer of sialic acid from CMP-sialic acid to galactose-containing substrates. The encoded protein, which is normally found in the Golgi but which can be proteolytically processed to a soluble form, is involved in the generation of the cell-surface carbohydrate determinants and differentiation antigens HB-6, CDw75, and CD76. This protein is a member of glycosyltransferase family 29. Three transcript variants encoding two different isoforms have been found for this gene.
General function
Apoptosis
Comment
Cellular localization
Cytoplasmic
Comment
Ovarian function
Follicle atresia, Luteinization
Comment
Kimura et al. (1999) showed that the lectin Sambucus sieboldiana agglutinin (SSA) specific for Siaalpha2,6Gal/GalNAc showed positive staining for granulosa cells only in atretic follicles of porcine ovaries by lectin histochemistry. . Reverse transcription-polymerase chain reaction analysis demonstrated that the expression of ST6Gal I mRNA was up-regulated in granulosa cells during atresia. These results suggested that the alteration of glycoconjugates by ST6Gal I in granulosa cells during atresia is involved in some processes of ovarian follicular atresia and granulosa cell apoptosis.
Expression regulated by
LH
Comment
Ovarian localization
Granulosa, Luteal cells
Comment
Augustin et al. (1995) reported that Northern blot analysis of glycosyltransferases during the different stages of angiogenesis revealed an up-regulation of beta-galactoside alpha 2,6-sialyltransferase and alpha 1,3-galactosyltransferase mRNA expression during the angiogenic stages of corpus luteum formation.