HARE-Mediated Endocytosis of Hyaluronan and Heparin Is Targeted by Different Subsets of Three Endocytic Motifs

Table 1

Endocytosis of Hep or HA by WT or HARE CD mutants.

HARE; variant	Hep endocytosis; (fmol/10^6 cells/HARE/h)	Specific Hep; endocytosis (%)	Specific HA; endocytosis (%)	HA endocytosis; (fmol/10^6 cells/HARE/h)
EV	110 ± 10	0	0	29.1 ± 2.8
HARE (WT)	480 ± 20	100	100	1204 ± 89
ΔM1		65	51	—
ΔM2		135	61	—
ΔM3		35	44	—
ΔM4		68	119	—
+M2	111 ± 30	0	0
+M3		65	58	—
+M4	129 ± 10	5	0
+M3  (Y2519A)		0	5	—
WT (Y2519A)	460 ± 30	95	94	—

EV, WT HARE, or the indicated HARE CD mutant cells were assessed for their ability to endocytose ¹²⁵I-labeled Hep or HA specifically and results were normalized to total protein (cell number) and HARE expression level relative to WT as described in Methods section. Values are the mean ± SE () rate of endocytosis or the rate of specific endocytosis (uptake by WT cells minus uptake by EV cells) relative to WT as 100%; significant differences compared to WT are indicated: ; . The relative specific HA endocytosis values for the CD variants examined previously [26] are included (third column), along with the HA values for +M2 and +M4 cells determined here (far right column), for comparison to the Hep endocytosis values. The single-motif deletion mutant cells (ΔM2 and ΔM4) that show differential involvement in HA versus Hep endocytosis are highlighted (boldface font).