姓
xìng
Using the verb "xing"
姓 is a verb meaning "to have the surname" — no 是, no 叫.
Subj. + 姓 + Surname
How it works
你姓什么? is the polite way to ask a surname; 我姓王 is the answer. 我是姓王 is wrong.
The very polite form is 您贵姓? — literally "your honourable surname?" — answered modestly with 免贵姓王 or simply 我姓王.
姓 takes only the surname. Full names go with 叫: 我姓王，叫王明.
Examples
nǐ xìng shén me?
你姓什么？
What's your surname?
wǒ xìng wáng
我姓王。
My surname is Wang.
nín guì xìng?
您贵姓？
May I ask your surname?