Table 1.

Structural, biochemical, and genetic characteristics of six different types of Insulin-like growth factor binding proteins (IGFBPs).

Properties	IGFBP1	IGFBP2	IGFBP3	IGFBP4	IGFBP5	IGFBP6
Molecular weight (KDa)	25–30	31	28–31	25-28	29	22–25
No. of amino acids	243	289	264	237	252	216
No. of cysteines	18	18	18	20	18	16
Chromosomal localization	7p	2q	7p	17q	2q	12
Glycosylation sites	No	No	Yes	Yes	Yes	Yes
Heparin-binding domain	No	Yes	Yes	No	Yes	Yes
Binds to ECM or cell surface	No	Yes	Yes	No	Yes	No
Binds to ALS	No	No	Yes	No	Yes	No
Nuclear localization sequence	No	Yes	Yes	No	Yes	Yes