galectin-1 is secreted into the extracellular space despite lacking signaling sequences required for secretion via the standard endoplasmic reticulum/Golgi pathway.
Extracellular galectin-1 has a slightly higher molecular weight (15 kDa) than the 14 kDa form found in cell lysates, suggesting
that the secreted galectin-1 undergoes further post-transational modifications before or after secretion [49].
It was demonstrated
that extracellular 15 kDa galectin-1 is able to bind to cell surface
at specific locations. Since galectin-1 lacks the required signal peptide
for secretion pathways, authors suggested that post-translational
modifications, resulting in the high galectin-1 molecular
mass, are required for galectin-1 export to the extracellular compartmentpartment.