Galectin-9 Antibody (Rabbit mAb) [K4C23]

Application: Reactivity: Human

Usage Information

Dilution
WB1:1000 IHC1:1000 IF1:250 FCM1:500

Application
WB, IHC, IF, FCM

Reactivity
Human

Source
Rabbit Monoclonal Antibody

Storage Buffer
PBS, pH 7.2+50% Glycerol+0.05% BSA+0.01% NaN3

Storage (from the date of receipt)
-20°C (avoid freeze-thaw cycles), 2 years

Predicted MW Observed MW
40 kDa 34-39 kDa, 13-15 kDa
^*Why do the predicted and actual molecular weights differ? The following reasons may explain differences between the predicted and actual protein molecular weight. Post-translational modifications(e.g., phosphorylation, glycosylation); Splice variants and isoforms; Relative charge; Multimerization.

Positive Control	Human colon tissue; Human liver tissue; A549 cells; THP-1 cells; HL-60 cells; U-937 cells; MOLT-4 cells
Negative Control	PANC-1 cells; HEK-293T cells

Datasheet & SDS

Biological Description

Specificity
Galectin-9 Antibody (Rabbit mAb) [K4C23] detects endogenous levels of total Galectin-9 protein.

Clone
K4C23

Synonym(s)
Galectin-9, Gal-9, Ecalectin, Tumor antigen HOM-HD-21, LGALS9

Background
Galectin-9 belongs to the tandem-repeat subfamily of galectins, built from two carbohydrate recognition domains connected by a linker sequence, and this bivalent architecture allows a single Galectin-9 molecule to crosslink glycosylated cell-surface receptors into multivalent galectin-glycoprotein lattices that regulate downstream signaling. Galectin-9 functions as the ligand for TIM-3, a cell-surface molecule expressed specifically on Th1 effector cells, exhausted CD8-positive T cells, and resting monocytes and macrophages, and engagement of TIM-3 by Galectin-9 triggers an intracellular calcium flux in a strictly TIM-3-dependent manner, which drives cell aggregation and subsequent death of Th1 cells; administration of Galectin-9 in vivo produces selective loss of interferon-gamma-producing cells and suppresses Th1-driven autoimmunity, directly demonstrating that the Galectin-9-TIM-3 pathway functions as a terminator of effector Th1 responses rather than a general immunosuppressive signal. This calcium-triggered death pathway proceeds through downstream calpain and caspase-1 activity, and because TIM-3 expression marks activated rather than naive T cells, Galectin-9's cytotoxic effect is selectively targeted to effector populations that have already upregulated TIM-3, sparing resting lymphocytes from the same signal. Beyond this canonical TIM-3-dependent apoptotic mechanism, Galectin-9 also engages the inhibitory receptor PD-1, and PD-1 binding to Galectin-9 physically attenuates Galectin-9/TIM-3-induced T-cell death, providing a molecular explanation for why PD-1-positive, TIM-3-positive exhausted T cells persist in the tumor microenvironment despite carrying the death-inducing TIM-3 receptor, since PD-1 co-expression protects these cells from Galectin-9-driven apoptosis that would otherwise eliminate TIM-3-single-positive cells. Selectively blocking Galectin-9 with a neutralizing antibody expands intratumoral TIM-3-positive cytotoxic CD8 T cells as well as immunosuppressive regulatory T cells, and combining anti-Galectin-9 therapy with an agonistic antibody targeting the costimulatory receptor GITR to deplete regulatory T cells produces synergistic antitumor activity, directly linking the PD-1-Galectin-9-TIM-3 interaction network to a therapeutically actionable checkpoint distinct from PD-1/PD-L1 blockade alone. Galectin-9 expression and secretion are induced by type I and type II interferons, and elevated Galectin-9 expression correlates with poor prognosis across multiple human cancers.

Background

Galectin-9 belongs to the tandem-repeat subfamily of galectins, built from two carbohydrate recognition domains connected by a linker sequence, and this bivalent architecture allows a single Galectin-9 molecule to crosslink glycosylated cell-surface receptors into multivalent galectin-glycoprotein lattices that regulate downstream signaling. Galectin-9 functions as the ligand for TIM-3, a cell-surface molecule expressed specifically on Th1 effector cells, exhausted CD8-positive T cells, and resting monocytes and macrophages, and engagement of TIM-3 by Galectin-9 triggers an intracellular calcium flux in a strictly TIM-3-dependent manner, which drives cell aggregation and subsequent death of Th1 cells; administration of Galectin-9 in vivo produces selective loss of interferon-gamma-producing cells and suppresses Th1-driven autoimmunity, directly demonstrating that the Galectin-9-TIM-3 pathway functions as a terminator of effector Th1 responses rather than a general immunosuppressive signal. This calcium-triggered death pathway proceeds through downstream calpain and caspase-1 activity, and because TIM-3 expression marks activated rather than naive T cells, Galectin-9's cytotoxic effect is selectively targeted to effector populations that have already upregulated TIM-3, sparing resting lymphocytes from the same signal. Beyond this canonical TIM-3-dependent apoptotic mechanism, Galectin-9 also engages the inhibitory receptor PD-1, and PD-1 binding to Galectin-9 physically attenuates Galectin-9/TIM-3-induced T-cell death, providing a molecular explanation for why PD-1-positive, TIM-3-positive exhausted T cells persist in the tumor microenvironment despite carrying the death-inducing TIM-3 receptor, since PD-1 co-expression protects these cells from Galectin-9-driven apoptosis that would otherwise eliminate TIM-3-single-positive cells. Selectively blocking Galectin-9 with a neutralizing antibody expands intratumoral TIM-3-positive cytotoxic CD8 T cells as well as immunosuppressive regulatory T cells, and combining anti-Galectin-9 therapy with an agonistic antibody targeting the costimulatory receptor GITR to deplete regulatory T cells produces synergistic antitumor activity, directly linking the PD-1-Galectin-9-TIM-3 interaction network to a therapeutically actionable checkpoint distinct from PD-1/PD-L1 blockade alone. Galectin-9 expression and secretion are induced by type I and type II interferons, and elevated Galectin-9 expression correlates with poor prognosis across multiple human cancers.

References
https://pubmed.ncbi.nlm.nih.gov/33547304/ https://pubmed.ncbi.nlm.nih.gov/16286920/

Protein Size (kDa)	PVDF Transfer Membrane Pore Size (μm)
< 10	0.22
10-20	0.22
20-30	0.45
30-45	0.45
45-70	0.45
80-100	0.45
100-140	0.45
> 140	0.45

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Protein Size (kDa)	Separating Gel Percentage
4-40	20%
12-45	15%
10-70	12.5%
15-100	10%
25-100	8%
60-210	5%