Poutasi announced on Twitter that Vaelua Poutasi, his mother, died in the afternoon of complications from diabetes.
Earlier in the day, Poutasi tweeted a photo of him visiting his mother in a hospital room, where he reportedly went immediately after signing and faxing his national letter of intent to the Golden Bears.
Poutasi is a 6-foot-4, 305-pound lineman from Las Vegas Desert Pines. He is ranked 61st at his position by ESPN in the Class of 2017 and is the ninth-ranked recruit in Nevada.
He was also considering Arizona, Colorado State, Hawaii, Louisville, San Diego State, UCF and UNLV.
Cal coach Justin Wilcox glowed about Poutasi's early-impact potential at a national signing day news conference Wednesday before addressing news of Poutasi's mother.
"Our thoughts and prayers go out to him and his family," Wilcox said. "We'll do whatever we can to support him."