The domains of Nell-1 and Nell-1’s isoforms as well as the known functions of
Nell-1. (A) Nell-1 has a length of 810 amino acids and is
composed by a secretion signal peptide, an NH2-terminal von Willebrand
factor C (vWC) domain, 4 vWC domains, and 6 epidermal growth factor–like
(EGF) domains. Nell-1 short isoform, also known as Nell-1 570, is an
N-terminal-truncated Nell-1 isoform. Nell-1-ΔE is lacking 1 calcium-binding
EGF-like domain. The molecular weight of the full-length Nell-1 and its
isoforms before and after posttranslational modifications (PTMs) based on
previous publications are stated in the figure. The LamG domain of Nell-1
can bind to apoptosis-related protein 3 (APR3), heparin, and
contactin-associated protein-like 4 (Cntnap4). The CC region is in charge of
the formation of homo-oligomers. The EGF domains can bind to protein kinase
C βI (PKCβI), while the second and third EGF domains can also bind to
roundabout 2 (Robo2). The last 2 vWC domains can bind to integrin α3β1.
(B) The current known functions of Nell-1.