Type II domain is approximately sixty amino acids long,[4] contains four conserved cysteines involved in disulfide bonds and is part of the collagen-binding region of fibronectin. Type II domains occur two times in fibronectin. Type II domains have also been found in a range of proteins including
blood coagulation factor XII; bovine seminal plasma proteins
PDC-109 (BSP-A1/A2) and
BSP-A3;[5] cation-independent mannose-6-phosphate receptor;[6] mannose receptor of macrophages;[7] 180 Kd secretory phospholipase A2 receptor;[8] DEC-205 receptor;[9] 72 Kd and 92 Kd type IV collagenase (
EC3.4.24.24);[10] and hepatocyte growth factor activator.[11]
Fibronectin type II domain and Lipid bilayer interaction
Fibronectin type II domain is part of the extracellular portions of EphA2 receptor proteins. FN2 domain on EphA2 receptors bears positively-charged components, namely K441 and R443, which attract and almost exclusively bind to anionic lipids such as anionic membrane lipid phosphatidylglycerol.[12] K441 and R443 together make up a membrane-binding motif that allows EphA2 receptors to attach to the cell membrane.[12]
^Kornfeld S (1992). "Structure and function of the mannose 6-phosphate/insulinlike growth factor II receptors". Annu. Rev. Biochem. 61 (1): 307–330.
doi:
10.1146/annurev.bi.61.070192.001515.
PMID1323236.