Thyroid-stimulating hormone (
TSH) alpha- and beta-subunit glycosylation was investigated in mouse thyrotropic
tumor and in normal and hypothyroid pituitary cells for various periods of time in the presence of [3H]
mannose or [3H]
galactose. After sequential precipitation with anti-alpha and anti-beta sera, subunits were treated with
Pronase followed by
endo-beta-N-acetylglucosaminidase H (Endo H) and analyzed by paper chromatography. In primary cultures of thyrotropic
tumor cells incubated for 60 min with [3H]
mannose, primarily
Man9GlcNAc and Man8GlcNAc were found on
TSH + alpha subunits, whereas Glc1Man9GlcNAc and
Man9GlcNAc were prominent on free beta subunits. After preincubation of cells for 16 h in the presence or absence of
glucose followed by a 60-min pulse of [3H]
mannose, there was an 8-fold increase in labeled
TSH + alpha but only a minimal change in free beta or total
proteins. In the absence of
glucose, there was a selective accumulation of Man8GlcNAc on
TSH + alpha but not on free beta or total
proteins; however, there was no detectable accumulation of Endo H resistant forms during
glucose starvation on TSH subunits or total
proteins. Normal mouse and rat pituitary minces incubated for 60 min with either [3H]
mannose or [3H]
galactose showed no
glucose-containing species on TSH subunits, but equal amounts of
Man9GlcNAc and Man8GlcNAc on
TSH + alpha, and mostly
Man9GlcNAc on free beta subunits. In contrast, hypothyroid mouse and rat pituitaries exhibited an increase in Glc1Man9NAc and Glc1Man8GlcNAc on free beta but not on
TSH + alpha or total
proteins.(ABSTRACT TRUNCATED AT 250 WORDS)