Ownership Submission

FORM 3

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940

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(Print or Type Responses)

1. Name and Address of Reporting Person ^*

SEIDENBERG BETH C

2. Date of Event Requiring Statement (Month/Day/Year)
10/15/2014

3. Issuer Name and Ticker or Trading Symbol
Atara Biotherapeutics, Inc. [ATRA]

(Last)

(First)

(Middle)

2750 SAND HILL ROAD

4. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

__X__ Director	__X__ 10% Owner
_____ Officer (give title below)	_____ Other (specify below)

5. If Amendment, Date Original Filed(Month/Day/Year)

(Street)

MENLO PARK, CA 94025

6. Individual or Joint/Group Filing(Check Applicable Line)
_X_ Form filed by One Reporting Person
___ Form filed by More than One Reporting Person

(City)

(State)

(Zip)

Table I - Non-Derivative Securities Beneficially Owned

1.Title of Security (Instr. 4)	2. Amount of Securities Beneficially Owned (Instr. 4)	3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	4. Nature of Indirect Beneficial Ownership (Instr. 5)
Common Stock	746,923	I	See Footnote ⁽¹⁾
Common Stock	22,307	I	See Footnote ⁽²⁾

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.			SEC 1473 (7-02)
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Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)

1. Title of Derivative Security (Instr. 4)	2. Date Exercisable and Expiration Date (Month/Day/Year)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
1. Title of Derivative Security (Instr. 4)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	4. Conversion or Exercise Price of Derivative Security		6. Nature of Indirect Beneficial Ownership (Instr. 5)
Series A Preferred Stock	⁽³⁾	⁽³⁾	Common Stock	1,244,871	$ ⁽³⁾	I	See Footnote ⁽¹⁾
Series B Preferred Stock	⁽³⁾	⁽³⁾	Common Stock	607,234	$ ⁽³⁾	I	See Footnote ⁽¹⁾
Series A Preferred Stock	⁽³⁾	⁽³⁾	Common Stock	37,179	$ ⁽³⁾	I	See Footnote ⁽²⁾
Series B Preferred Stock	⁽³⁾	⁽³⁾	Common Stock	18,136	$ ⁽³⁾	I	See Footnote ⁽²⁾

Reporting Owners

Reporting Owner Name / Address	Relationships
Reporting Owner Name / Address	Director	10% Owner	Officer	Other
SEIDENBERG BETH C 2750 SAND HILL ROAD MENLO PARK, CA 94025	X	X

Signatures

/s/ Paul Vronsky, Attorney-in-Fact		10/15/2014
^**Signature of Reporting Person		Date

Explanation of Responses:

*	If the form is filed by more than one reporting person, see Instruction 5(b)(v).
**	Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1)	The shares are directly held by Kleiner Perkins Caufield & Byers XV, LLC ("KPCB XV"). All shares are held for convenience in the name of "KPCB Holdings, Inc., as nominee". The managing member of KPCB XV is KPCB XV Associates, LLC ("XV Associates"), of which the Reporting Person is a member. The voting and dispositive control over the shares is shared by the managing members of XV Associates and the Reporting Person.
(2)	The shares are directly held by KPCB Founders Fund, LLC ("KPCB XV FF"). All shares are held for convenience in the name of "KPCB Holdings, Inc., as nominee". The managing member of KPCB XV FF is XV Associates, of which the Reporting Peron is a member. The voting and dispositive control over the shares is shared by the managing members of XV Associates and the Reporting Person.
(3)	Each share of Series A Preferred Stock and Series B Preferred Stock is convertible into one share of Common Stock without payment of further consideration and will automatically convert into one share of Common Stock upon the closing of the Issuer's initial public offering without payment of further consideration. The shares have no expiration date.
Remarks: The Reporting Person disclaims beneficial ownership of these shares except to the extent of any pecuniary interest therein, and the filing of this report is not an admission that the Reporting Person is the beneficial owner of these shares for purposes of Section 16 or for any other purpose.

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