Why does the (N)KJV put Jesus' name in all caps in Matthew 1:21 and Luke 1:31?

It's only in the King James and the New King James, but why is Jesus' name in all caps? > And she shall bring forth a son, and thou shalt call his name JESUS: > for he shall save his people from their sins.**Matthew 1:21** > > And, behold, thou shalt conceive in thy womb, and bring forth a son, > and shalt call his name JESUS. **Luke 1:31** It isn't like this anywhere else in the Bible. The word in the Greek is the same as in other instances of the name. Why? And why only in the KJV?